The Thomist 68 (2004): 105-41


                                                                        Michael Augros

                                                                                                 Waterbury, Connecticut

The development of science has shaped or influenced virtually every aspect of modern culture. One of its consequences has been the apparent demise of natural philosophy, which was perceived to be an erroneous first attempt to do what science now does correctly. To this day one sees on occasion a physics textbook that begins by censuring Aristotle, the natural philosopher par excellence, for his blunders about falling bodies, or the stars, or the elements. Some historians concede that we could hardly have expected more from the Philosopher, helpless as he was without telescopes and other scientific paraphernalia. Others point out that he himself offered apology for daring to speak on things unobservable to him:

We regard the zeal of one whose thirst after philosophy leads him to accept even slight indications where it is very difficult to see one's way, as a proof rather of modesty than of over-confidence.(1)

By the kinds of experience available to him, Aristotle could never have attained to much more than scanty conceptions about the stars. He could not correctly identify even the elements of familiar and humble Earth. It seemed only appropriate that philosophers

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should have relinquished the whole study of nature to those better equipped for the job.(2)

Philosophers, however, cannot afford this luxury. Once every attempt to philosophize about nature is abandoned, what becomes of philosophy? What is left? Shall we philosophize about God? Or the immortality of the soul? If the principles and methods of philosophy prove unreliable regarding things we can lay our hands on, can we trust them in studying things outside our experience? Incredible. Worse yet, if philosophers give up talking about the natural world altogether, then ethics, too, despite its preoccupation with our very own actions, could not go forward without permission from the scientists, but would be obliged to wait upon their final verdict concerning, for example, the question of human freedom. When scientists, using only the methods to which they are accustomed, see no need for such things as free will, the soul, purpose in nature, and a host of other things, they are apt to regard them as obsolete hypotheses invented in a time when a sober study of nature was neither possible nor yet conceived, when people had an animistic and anthropomorphic view of the world. In other words, natural philosophers are not extinct; they have disappeared from philosophy departments only to reappear in science departments.

There has been for some time now an unfortunate divorce between "science" and "natural philosophy," a divorce which I am to some extent forced to acknowledge because of common parlance. Although there is a real difference between the methods used in the more general study of nature and those used in the

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more detailed studies of it, such differences do not warrant a distinction of disciplines. One and the same discipline can require many different methods in order to approach its one subject matter. Physicists sometimes use thought experiments, other times they perform physical experiments. Astronomers sometimes use optical telescopes, other times they need radio telescopes. Biologists sometimes observe the whole animal in action, other times they dissect it. Nevertheless, most philosophers who have not given up on nature entirely have restricted "the philosophy of nature" to the most general study of nature, where, as we shall see, certainty is attainable and hypotheses and experiments are unnecessary. Meanwhile, scientists have confined "science" to a study of nature by means of hypotheses and experiments. It was not always so. In Aristotle's day, indeed in the time of Thomas Aquinas, there was no distinction between the philosopher of nature and the scientist. Natural science is one philosophic discipline, although it requires many different methods. Even by Newton's time it was still customary to call physics "philosophy."(3)

The distinction between natural philosophy and science is certainly artificial for any lover of wisdom who wishes to understand all things as much as possible. A study that begins in wonder(4) could hardly stop just as the most wonderful questions emerge, for the mere reason that we cannot have certainty about the answers. For scientists, too, the distinction is unnatural. If they study nature out of curiosity about it, will they ignore any source of genuine knowledge about it? Will they not rather rejoice at the possibility of knowing with certainty at least some things about nature, however humble and general? It makes no sense to distinguish two disciplines that seek to understand the same subject matter in the same light, namely, the light of sense

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experience. To number disciplines based on the number of methods used is backwards: subject matter is much more fundamental.(5) If we define a discipline by a single method, then its subject matter becomes "whatever can be understood by that method." Accordingly, "the philosophy of nature" has for its subject matter "whatever can be understood about nature with certainty from general experience," and the subject matter of "science" becomes "whatever can be learned about nature by experiments."(6)

It is no doubt true that the generic study of nature is more "philosophical" than the detailed study of it in the sense that the way of thinking appropriate to this study resembles metaphysics more than modern physics does. It is a mistake, however, to conclude that thinking in very general terms is somehow more "philosophical" than getting down to particulars. A philosopher is not someone who prefers thinking about "animal" rather than "slug." Ideally, Aristotle says,

We proceed to treat of animals, without omitting, to the best of our ability, any member of the kingdom, however ignoble. For if some have no graces to charm the sense, yet even these, by disclosing to intellectual perception the artistic spirit that designed them, give immense pleasure to all who can trace links of causation, and are inclined to philosophy.(7)

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As for which is more "scientific," the general or the particular knowledge of nature, this depends entirely on what is meant by the word. In its ancient sense, scientia or epistm meant a very perfect knowledge, a certainty of something obtained by seeing the reasons why it is so. Accordingly, mathematics would be the most scientific of the sciences, as one can judge by the standards laid out for "science" in Aristotle's Posterior Analytics. In this sense of "science," the more general study of nature is more "scientific," because it is much more certain than the detailed study of nature which rests upon hypotheses.

Today, however, the word "science" has a meaning that does not apply to mathematics at all.(8) It means a knowledge obtained by experimentation, and the testing of hypotheses. Notice that this new meaning is not given in terms of the subject matter we hope to understand, but in terms of a particular method of understanding it.(9) It follows, of course, that a generic understanding of natural things, which does not need experiments at all, is not "science." Some would even call it "unscientific," implying, unjustly, that whatever does not use the experimental method cannot be real knowledge, but is more like conjecture or groundless opinion. Regardless of the motives for restricting the word "science" in this way, taken in this sense it is clear that the more detailed parts of the study of nature are more "scientific."

To sum up, if "philosophy" is taken in its ancient sense to mean any universal knowledge (or search for it) beginning in wonder, it applies to the whole study of nature, both general and specific, and if more to either, more to the specific, since a knowledge of things in all their concreteness is more wonderful than a general understanding of them that abstracts from their

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differences. Thus what we call "science" today would be more "philosophical" than Aristotle's Physics. If "science" is taken in its ancient sense to mean a very sure and causal knowledge of conclusions, then it applies more to the more general study of nature, and thus Aristotle's Physics would be more "scientific" than what we call "science" today.

The more general study of nature I will call "natural philosophy," and the more detailed study of it, "science." Using this distinction, we may say that it is generally thought today that science does not continue the philosophy of nature, but replaces it. The detailed study of nature, based on experiments, is the only serious knowledge of nature, we are told, and it replaces the more general study of it conducted by philosophers who do not use experiments.(10) To see clearly whether the more "scientific" study of nature can replace the more "philosophic," to see how these methods are related, it is necessary first to see their distinction. Scientists might resent being told that theirs is only a part of the study of nature, that there are ways to study nature other than the ones they commonly adopt, ways that yield a knowledge worthy of the name. Science tends to define itself with perfect generality: any and all genuine knowledge of the natural world is "science." This is as it should be, and it is the way Aristotle understood the science of nature. There are nonetheless principles and methods, and even kinds of experience, that scientists almost entirely ignore, but that if pursued yield genuine knowledge of the natural world.

All distinction is based on some kind of opposition. Distinguishing the more "philosophical" study of nature from the "scientific" accordingly reduces to understanding six(11) oppositions, which I now take up one at a time.

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I. General vs. Particular

The first difference between a more philosophic study of nature and what we today would call the scientific approach is based on the difference between generality and particularity. Science indisputably yields a much more distinct and detailed picture of the universe than philosophy can ever provide. A natural philosopher can show that locomotion is the most basic kind of change, and all other change depends upon it in some way.(12) A scientist can show how this is so in particular cases, for example showing how a change in temperature follows upon a change in the motions of tiny particles. A natural philosopher defines "element," and can show that elements must exist and that there must be a finite number of these in the world.(13) The scientist can tell what the chemical elements are, and he learns more every day about the ultimate particles composing all bodies. The natural philosopher argues that the universe is finite.(14) The scientist can tell roughly how much mass the universe contains, and whether the finitude of the universe is due to its having a boundary. The natural philosopher can say what time is.(15) The scientist can tell whether or not there is some universal standard of time in the universe. Thus scientists speak in a more particular and detailed way than natural philosophers do.(16)

In terms of detail science improves upon what natural philosophy has to say. A more particular knowledge is better than a more general, vague knowledge. It does not follow, however, that scientific knowledge of the natural world can replace a

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philosophic knowledge of it. Particular knowledge cannot replace general knowledge. One reason for this is that more general knowledge, precisely because it is more general and therefore less perfect, is also easier and more certain to us than an exacting knowledge of particulars.(17) And more certain knowledge cannot be replaced by less certain knowledge.

To illustrate, even when blindfolded I can distinguish between wine and beer. That is easy enough, being a quite general knowledge of rather major differences between different kinds of alcoholic beverages. I boast that I can also infallibly tell a white wine from a red one by blind tasting. Once I am asked about different reds, though, I get nervous. When we descend into different particular Zinfandels, or different years of the same Zinfandel, I am lost. Now even if I were a true connoisseur my knowledge of the differences between this and that wine could never replace my knowledge of the difference between wine and beer. It can complete it in some way, but never replace it.

The same is true of intellectual knowledge. My knowledge of the differences between the species of triangles cannot replace my more general knowledge of the differences between triangles and quadrilaterals. My knowledge of properties belonging to all triangles in general cannot be replaced by my knowledge of the properties belonging to the "three-four-five" right triangle in particular. In the opening chapter of his Physics, Aristotle points out that it is natural for us to begin the study of nature in a very general way, and that we are much more certain in our vague general knowledge than in our understanding of specific details. We are much more certain that there is a difference of kind between plants and animals than that there is such a difference between a skunk and a horse, and we are more certain that there is a difference of kind between a skunk and a horse than that there is such a difference between a horse and a zebra.

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It is better, then, to say that science completes natural philosophy in some way, rather than to say that it replaces it. A particular knowledge of the natural world is more perfect than a general knowledge of it, being more distinct and detailed, but it is also less general and less certain, and therefore cannot replace it.

II. Universal Experience vs. Confined Experiences

The second difference between natural philosophy and science is based on the kinds of experience from which they begin. I call "universal experience" the experience that all healthy adults have and cannot avoid having, and "confined experiences" any of the sort that only some people have.(18) Everyone experiences motion or change in the world; that is a matter of universal experience. But only some people experience earthquakes; that kind of experience is confined to certain individuals, even if a great number of them. Every healthy adult has an experience of seeing; that is again a matter of universal experience. The more particular experience of seeing the northern lights, however, is restricted to some people only. Experiencing hallucinations, or experiencing heightened senses of hearing and smell due to loss of vision, are also matters of confined experience.

The answers to some fundamental questions about nature can be reached by beginning from nothing more than universal experience. Accordingly the first part of the study of nature begins from universal experience alone, but can take us only so far into a study of natural things. Not everything we wish to know about nature is contained implicitly in the kinds of experiences that all of us share. Science accordingly seeks to supplement ordinary experience by contriving, with instruments and experiments, further experiences that are necessarily confined to a few

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observers. Yet science takes pains to ensure that the kinds of observations from which it begins will always be reproducible in principle--they must be things which every person could in principle experience, even if it is not the case that every person must experience them.(19) Those who love knowledge are not satisfied with the scanty conceptions of so many particular things which universal experience by itself would supply--we must pursue a more and more detailed experience of nature. Thus it is a part of the aim of science to extend the range of our experience.(20)

The scientist is therefore more free to investigate whatever questions he chooses than his more philosophical counterpart. But his freedom is bought at a price: to begin from experiences that are not shared by all people, to which in fact only a very few are privy, inevitably introduces an element of human faith into science which is foreign to philosophy. Not only does a layman have to take a scientist's word for it that observations and experiments bear out his theory, but even the scientist himself must take his fellow scientists' word for such things. No scientist can personally verify in his own experience all the scientific theories and results upon which his own efforts depend. The philosopher, on the other hand, who does not descend to the more particular experiences of the scientist, is restricted to the investigation of those mysteries to which nature itself has seen fit to give us clues; he begins only from things that are naturally experienced by everyone. His advantage is that he need not put his faith in anyone to know his conclusions, since they rely upon no one's experience but his own. Once more, then, we have a reason that scientific knowledge of nature cannot replace a philosophical knowledge of it: a knowledge that relies on trusting someone else cannot replace a knowledge that does not.

It is important to underscore that science, too, presupposes and depends on universal experience; it is not possible to begin from

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confined experiences alone. What distinguishes the general part of the study of nature from science is not that it begins from universal experience, but that it restricts itself to this. The scientist, when describing or conducting an experiment or observation, relies upon the same common conceptions of the world that everyone does, even if he is not restricted to these.(21) The principle that "The whole is greater than its part" applies in nature as well as in mathematics, and it is known to everyone since wholes and parts are a matter of universal experience. Where would science be if this principle were in doubt? And yet it is not the result of experimentation or contrived observation of any kind.

It is therefore useless to try debunking the philosophy of nature on the ground that science often overturns common experience. "Common experience," if taken to mean universal experience as defined above, is not only the basis of the more general philosophy of nature, but it is also one of the irreplaceable pillars of science. There is another sense of "common experience" or "common sense," however, which can be overturned by science.(22) Sometimes what everyone naturally thinks at first, before being taught otherwise, is called "common sense." Taken in this way, it is common sense, for example, that a sailboat cannot sail faster than the wind that is pushing it. Scientists and sailors assure us that this piece of "common sense" is actually false. It is noteworthy that even those who have never sailed before (perhaps I should say especially those who have never sailed before) will resist the notion that a sailboat can sail faster than the wind. Clearly their resistance is due not to any experience of sailboats but to their experience of some more

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general thing. They know that "No effect can exceed its cause." They are quite right about this; they are only mistaken in thinking that the sailboat sailing faster than the wind violates that principle. It is up to the physicists to explain how a sailboat can sail faster than the wind that is pushing it, without doing violence to that very general principle, upon which scientists also depend. Nor is science alone in this occasional overturning of "common sense." Philosophy too has its share of surprises.(23)


III. Reflective Experience vs. Unreflective Experience

There is another difference among the kinds of experience from which natural philosophy and science begin. Philosophy begins from both reflective and unreflective experience, whereas what we call "science" today more or less restricts itself to beginning from specific kinds of unreflective experience.

By "reflective experience" I mean what we experience whenever we reflect on any of our own acts of knowing or feeling or desiring. All other experience is unreflective. To see an apple is an unreflective experience, but to be aware that I am seeing an apple is a reflective one. To fear something is an unreflective experience, but to take note that I am fearing something is reflective. It is on the basis of reflective experience that I discern in myself the differences between remembering and imagining, for example.

It can easily be thought that what we experience within ourselves by reflection must be subjective and private, and therefore cannot serve as a reliable foundation for serious inquiry. But a little reflection reveals that this need not always be the case. A scientist would not be censured for claiming that water boils under certain conditions just because we could not be there to witness his water boiling; it is enough that we can witness this for

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ourselves with our own water if we take the trouble. Why should a matter of reflection be any different? It is true that someone else cannot share my reflection upon the goings-on of my own interior life, but surely he can verify within himself the kinds of experiences that I claim are the same for everyone. A trivial example: smells are evocative of memories more than colors or textures are. If one cannot reliably reflect on one's own knowledge, one could never know this.

Reflective experience is "subjective" in the sense that its object is something going on within the knowing subject, and it is inaccessible to those outside the subject. But it is not "subjective" in the sense that irrelevant features of the knowing subject are hopelessly confused with the object perceived. "How hot it feels to me" is a mixed result of the temperature of my hand and the temperature of what I am touching. My sensation alone cannot separate these. Therefore "how hot it feels to me" is "subjective" in the usual and somewhat pejorative sense of the word. But reflections such as "I am thinking right now," and "hearing is different from seeing," involve no such confusion.

Science generally limits itself to what can be known through unreflective, external experience. The physicist reads all his data off of instruments of measurement and observation. Even the biologist does not usually have recourse to the data of reflective experience. There is certainly some reasonable fear, in his case, of anthropomorphism, if he is studying anything other than human biology.(24) Yet it is equally possible to apply falsely the facts of unreflective external experience, so this can hardly be a reason for abstaining from the use of reflective experience altogether. Psychology, it is true, makes use of some data known only by reflective experience, but it is partly for this reason that the discipline is not considered one of the "hard" sciences, and some

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psychologists struggle to make their discipline more "scientific" by sticking to the data of external and measurable experience as much as possible.(25) If any part of psychology made full use of the data of reflective experience, it would look more and more like Aristotle's De Anima.

The scientist has no reason or need to deny the possibility of studying natural things, especially living things, with the help of reflective experience. Sir Arthur Eddington even remarks that a knowledge of the inner natures of things does not seem possible without it.(26)

IV. Natural vs. Artificial

The opposition between the natural and the artificial partly explains the distinction between the "philosophic" and the "scientific" approaches to nature. For one thing, there is a

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difference between natural experience, in which we play an almost exclusively passive role, and artificial experience, which we contrive for ourselves in some way. Insofar as science uses artificial instruments to extend the range of our experience, it can be said to proceed from "artificial" experiences. Even an experiment which does not use such artificial aids is to some extent an artificial experience, since it is not something that plays out naturally, as it would if left to itself, but it is something that an observer "sets up." J. Henri Fabre put it this way: "It is something to observe; but it is not enough: we must experiment, that is to say, we must ourselves intervene and create artificial conditions which oblige the animal to reveal to us what it would not tell if left to the normal course of events."(27)

The scientist consequently enjoys more freedom in his lines of questioning than does the philosopher of nature. This difference between them can be illustrated by the following proportions:(28)

Natural Philosopher : Nature :: Student : Teacher

Scientist : Nature :: Lawyer : Witness

There is an obvious similarity between these two proportions. The student hopes to learn something from the teacher, and likewise the lawyer hopes to learn something from the witness. The natural philosopher and physicist both hope to learn something from nature.

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But there are differences. The teacher is an initiator. He decides which topics to address, and which questions to answer. The student is not in a position to compel the teacher to address this issue or that, or to take things up in this or that order. The teacher will say many things, even if the student has not asked about them, and he might refuse to answer certain questions put to him by the student, deeming them inappropriate. When the natural philosopher studies nature, nature is like his teacher; he must listen(29) to what nature has to reveal about itself in natural experience, and content himself with whatever can be known by beginning from there. If he is not satisfied, but will compel nature to answer further questions, he is no longer like a student, but like a lawyer, with nature on the witness stand. The lawyer is the initiator and the witness does not speak except in answer to direct questions put to him by the lawyer. Nature must answer the questions put to it by the experimenter, but says no more to him than he has demanded with his experiment.

The natural philosopher distinguishes between the natural and the artificial, and then talks chiefly about the natural as such.(30) The physicist, on the other hand, can afford to ignore (though not

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deny) the distinction, because his metrical vocabulary ignores it.(31) Thus many, if not all, of the laws of physics apply equally well to both natural and artificial bodies without distinction. The path of a body launched over a cliff will approximate a semi-parabola whether the body be a horse or a piano. Physics textbooks abound with problems like this: "Consider a string stretched tightly . . ." or "Suppose a pulley is set up . . ". It makes not a whit of difference whether the string or pulley is a natural thing or an artificial one, so long as it meets the metric requirements of the problem.

Biology, too, can overlook the distinction between the natural and the artificial, studying in living things only what is common to them and machines. Nothing prevents this kind of study, and it is nothing short of amazing how much living things do have in common with machines, and so the biologists, while ignoring anything distinctive of living things, never run out of things to talk about.(32) But if biology were to deny the difference between the natural and the artificial it would find itself unable to designate its own proper subject matter.

It goes beyond the evidence to say that living things are nothing but machines, that they do not differ in principle from them. This was Descartes's vision of the world: what we call cats and dogs are no more than res extensa, cogs and wheels grinding away without purpose or interior life, mere mechanisms, not

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organisms.(33) Those overly enamored of the method of study based on unreflective external experience often succumb to the temptation of thinking theirs is the only legitimate study, that anything known only by reflecting within ourselves is material fit only for poets, for those who wish to emote, not those who would know anything about the world. How would such a person understand something as biological as sensation? He would have to reduce it to the things attendant upon it which he can observe with his "objective" methods--a hopeless endeavor. Erwin Schrödinger illustrates this point:

The sensation of colour cannot be accounted for by the physicist's objective picture of light-waves. Could the physiologist account for it, if he had a fuller knowledge than he has of the processes in the retina? I do not think so. We could at best attain to an objective knowledge of what nerve fibres are excited and in what proportion, perhaps even to know exactly the processes they produce in certain brain cells--whenever our mind registers the sensation of yellow. . . . But even such intimate knowledge would not tell us anything about the sensation of colour, more particularly of yellow. . . . the same physiological processes might conceivably result in a sensation of sweet taste, or anything else. I mean to say simply this, that we may be sure there is no nervous process whose objective description includes the characteristic yellow colour or sweet taste, just as little as the objective description of an electromagnetic wave includes either of these characteristics. The same holds for other sensations . . . neither the physicist's description, nor that of the physiologist, contains any trait of the sensation of sound. Any description of this kind is bound to end with a sentence like: those nerve impulses are conducted to a certain portion of the brain, where they are registered as a sequence of sounds. . . . We may follow this conduction to the cerebral cortex and we may even obtain some objective knowledge of some of the things that happen there. But nowhere shall we hit on this registering as sound, which simply is not contained in our scientific picture, but is only in the mind of the person whose ear and brain we are speaking of.(34)

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These words apply not only to the operations of the five senses, but to the operations of imagination, memory, to the emotions, to the will, and to the intellect. One would think that only a blind man could say that what we call seeing is nothing but these things he can record and observe from the outside of the one who is seeing. Has he never seen before? And if he has, how could he fail to realize that what he calls "seeing" in himself is precisely what he cannot see anywhere in the person he is observing? No matter how advanced his "objective" knowledge is, he will never observe sight in this way; he can witness only external signs, even if some of these are in some inscrutable way necessary for sight itself. None of them, and not even all of them together, is sight. There is no way to prove to a man that he has the ability to see colors if he discounts his own immediate experience of it.

If despite all this we insist on discarding all the data of reflective experience, it is sheer folly to demand that anyone show us evidence that living things differ from nonliving, or that animals differ from machines, or that natural things differ from artificial ones.(35) We have in advance not admitted into evidence the only kind of experience relevant to the question. We might as well demand that our neighbor prove there are two-inch fishes in the lake by means of a net with three-inch holes in it. If natural things and living things are precisely those which behave as they do because of some principle within themselves, a principle whose existence and nature would remain wholly unknown to us if we were incapable of reflecting on the operations of similar principles within ourselves, then to reject reflective experience as an

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unsound basis for knowledge is to reject such distinctions as unfounded. Imagine an impossible scenario: a man being born utterly unable to reflect upon or notice any of his own living operations in an inward way, but always having his attention fixed outward. He could see colors, but never notice that he was seeing; he could understand shapes, but never notice that he was understanding. Could he ever form the slightest notion of what was going on in the mind of a deer in the park when he saw it perk up its ears? The event, to him, would be a sudden change of position in a chunk of matter, perhaps following upon many other little changes of place in adjacent chunks of matter, no more. He could form no notion of "hearing." Nor, when the deer bolted away, could he form any notion of "afraid," although he might suspect, from prior "objective" investigations into similar moving things, that there were many particular electrical and chemical changes that preceded this brownish mass dashing away upon its four appendages. He could also form no notion of himself, as distinct from any other thing in his direct, outward-fixed experience.(36) To ignore what we know solely by reflection is to

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ignore our only source of insight into what is distinctive about being alive or natural. What proceeds from deepest within is a living operation, or at least a natural one; but whence it proceeds simply is not visible from without. "Nature loves to hide."(37)

To suppose that another human being enjoys sight within himself similar to the sight I experience directly only within myself is not anthropomorphic.(38) Based on the more generic outward similarities between myself and a dog or a horse, I can go a step further and surmise that such creatures also experience within themselves something like what I call sight in myself, although possibly less like it than what goes on in my fellow humans. This is what it means to believe in animals, as opposed to res extensa. To insist that these things are nothing more than what I say they are in terms drawn exclusively from my outward observation of them is not only arbitrary, but anthropomorphic in the worst way. It would require that things are nothing more than what I know them to be by means of my arbitrarily preferred method of studying them.

The scientist can, and often should, ignore the differences between living and nonliving, between natural and artificial. This does not warrant any denial of such distinctions. But ignoring them has a wonderful side-effect: scientific results bear fruit in the world of technology. How could they not? If all the rules should apply to artificial things as well as to natural things, insofar as science abstracts from the difference (especially when speaking in a mathematical way), we should be able to manufacture things according to the laws of physics and chemistry. And the benefit is mutual, since science advances along with the instruments of observation and measurement provided by engineering. More

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than that, technical advances are like the proof in the proverbial pudding for the particular theories that engendered them. The atom bomb was a sign that atomic physics was on to something.(39)

Natural philosophy, however, must be comparatively barren in this respect. How could it be of much practical value? It is chiefly about natural things precisely as natural, and so we cannot expect that what it says will be of any special help in producing artificial things. Moreover, it begins only from universal experience, forcing it to study things very much in general, whereas making and doing things requires a detailed knowledge. Finally, it makes no use of measurement, which is fundamental in the making of almost everything. On the other hand, natural philosophy is not dependent upon technological advances, needing no instruments of observation beyond those dispensed to everyone by nature. Natural philosophy is useful, however, for grounding ethics and metaphysics, for which end experimental science does not serve.

V. Quantitative vs. Qualitative

Most sciences, if not all, use measurement, and the more scientific sciences use it more.(40) Science, then, is not only qualitative, but quantitative also, whereas the philosophy of nature is not quantitative, at least not in the sense of using measurement. A scientific measurement is only a particular kind of confined experience, but it characterizes science to such an extent as to be worthy of separate mention.

Science gains definite advantages over philosophy by its use of measurement and other forms of technical observation. Only by these means is a wealth of data made available to us which otherwise would remain forever beyond our reach, because it is

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either outside the range of our senses, or too dangerous for us to sense directly, or both. And even when we can sense something directly, the scientist is right to feel unsatisfied with the imprecision of unaided sensation. To one person this feels hotter than that, to another that feels hotter than this. As long as our bodies are our thermometers, we are not using measuring instruments constructed in precisely the same way, and what my sense of touch registers is vague even to myself. What portion of "how hot it feels to me" is due to the temperature of the water and what portion is due to the temperature of my body? My sensation does not tell me. Nor does my sensation assign a precise number to "how hot it feels to me," a number that I can compare to "how hot that other thing feels to me" in an unambiguous and precise way. Raw sensation was never meant for scientific precision. And yet mathematical precision is crucial for unraveling many of nature's riddles. Accordingly physics not only restricts itself to unreflective experience, but to objects of unreflective experience that are external and precisely measurable.

Galileo is traditionally hailed as the father of modern physics. He wrote his Two New Sciences in dialogue form, in the tradition of Plato, who, in his Timaeus, hinted that nature can be understood in a mathematical way. Modern physics, then, is the ultimate development of an ancient Pythagorean suspicion, a suspicion that many deep secrets of nature can be deciphered only by the use of mathematics. This suspicion was reasonable in two ways: first, because reason very naturally inclines to understanding things mathematically, since mathematics is so accessible to the human mind and yields great certainty and precision; second, because even a superficial look at the natural world reveals a host of things displaying quantitative properties, such as the hexagonal form of water crystals and the spiral form of sunflowers and seashells.

For these reasons, "to understand" in physics, and in science generally, quite often means "to have an equation," which is a kind of understanding insofar as it reduces a chaotic multiplicity of things to an identity of some kind, finding something one or

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the same in the many and seemingly disconnected.(41) The scientist uses the language of mathematics as often as possible, and the more scientific the science, the more its results will be expressed in mathematical symbols and formulae rather than in words and sentences.

The scientist's preference for symbols and formulae has led some people to doubt whether any knowledge of natural things is possible in mere words. If our work-a-day words were a precise enough medium by which to express the truth about nature, then why would scientists not be content with them? It is certainly true that words are not suited to expressing the very technical and precise results of physics,(42) but this is not because words are hopelessly ambiguous and signify nothing solid and certain. If that were so, physics itself would be impossible, too, not just the philosophy of nature. Even the most obscure symbolism of the physicist ultimately depends upon ordinary language for its meaning.(43) What is the meaning of T in our equation? It is neither

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here nor there that we can replace it with a cumbersome word, such as "temperature," but it is of the essence that we can explain, in words, where the number came from for which T stands. The process of measurement or observation which is the source and meaning of every physical quantitative symbol in our equations cannot also be expressed in symbols; it is expressed in words only. If we do not understand the measurement or observation expressed in words, then the symbols and formulae are nothing but hieroglyphics or, at best, an exercise in pure mathematics.(44) The terms of physics are meaningless apart from the appliances we detect and measure things with,(45) and these appliances are ultimately understood in words.

Certainly mathematics sheds light on nature. But is nature nothing but quantities? Or is nature's quantitative aspect the only inroad to understanding it? If "understanding" is defined as "having an equation," then the answer is settled in advance. If, on

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the other hand, "understanding" is taken more broadly to mean any kind of insight into the what and why of things, we can legitimately ask: Can this be attained solely through measure-ment? How could one know that natural things were of such a nature as to be accessible only through measurement? Surely not through measurement. The only way to know this would be through a philosophical argument of some kind, in which case one would have discovered something about nature without measurement, and hence the position self-destructs. Besides, vague as it may be, I am sure that "Red is not the same as green," quite independently of any measurement or mathematics.(46) A scientist has neither any reason nor any need to deny that there might be ways of understanding nature besides the way of measurement.

VI. Self-evident Things vs. Hypotheses

The final opposition which is the basis for distinguishing between the philosophical and the scientific study of nature is the opposition between the self-evident and the hypothetical. "The whole is greater than its part," which is self-evident to everyone, is as true in the natural world as it is in mathematics. This is not a matter of mere induction, as if we were sold on the matter because we have seen so many wholes none of which failed to be greater than each of its respective parts. Should a science journal announce one day that rock samples have been found on Mars, some of which were only half their own size, we would suspect a misprint, a practical joke, or lunacy. This is not a matter of "seen it so many times I would be surprised to find a counter-example," as in the case of having seen so many white swans, we are surprised to hear that there are black ones in Australia. It is a matter of the self-evident. It is from truths of this kind that the philosophy of nature begins. Such self-evident principles are relatively few, and rather general, although some are more specific than "The whole is greater than its part." We see once

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more that the philosophy of nature has a limited scope of inquiry, if it is defined as proceeding from such principles alone.

Science, on the other hand, begins from assumptions, from hypotheses, which though they are based on much experience and reasoning, nonetheless remain hypotheses. The scientist often reasons as follows:

If hypothesis Z is correct, then I should observe Q.

But I do observe Q.

Therefore hypothesis Z is somewhat confirmed.

He cannot conclude "hypothesis Z is correct," since that would amount to committing the fallacy of affirming the consequent. But the more often he reasons this way, and the more consequences of hypothesis Z that are confirmed, the more likely his hypothesis becomes. This is especially true if the consequences of the hypothesis are things never before observed or suspected, that is, if the hypothesis leads scientists to augment their experience. For all that, though, the hypothesis could still be false, merely resembling the true cause and producing similar consequences as far as we have seen. Einstein states it vividly:

Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all the things he observes, but he may never be quite sure his picture is the only one which could explain his observations.(47)

The use of the phrase "free creations" is worth remarking upon. Physical concepts and physical theories are in large part a product of the imagination, and "Nothing is more free than the imagination of man."(48) The imagination plays a much larger role

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in modern physics(49) than it does in natural philosophy. In natural philosophy, the first concepts, such as "motion," "body," "time," and the first self-evident statements such as "All change requires a subject" are not free creations of the human mind. Aristotle speaks more as if the truth of these things coerces the minds of men.(50) The natural philosopher needs some imagination and some use of dialectical hypothesis in order to discover the truth, but only on the way to acquiring the kind of knowledge he seeks. In a similar way, a mathematician might suppose something he is not sure about and see where it leads, but his work is not done until he finds a proof for his supposition that takes it back to self-evident principles which he knows to be true beyond doubt.

Science also lays down many things as facts which, in some measure at least, are really hypotheses, being the results of imperfect inductions. Scientists assume that water always boils under given conditions, not because they have seen every case, but because they have seen many cases, and they assume a kind of uniformity in nature.(51) Should they find something about water that is the reason why it boils under those given conditions, this something about water will in turn be something they have found to be so in all cases they have seen, and which they assume to belong to water in all cases. What is the difference between "Water boils at such-and-such a temperature and pressure" and "The whole is greater than its part"? Why have we no assurance of the first of these except our oft-repeated experience, but our

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assurance of the second seems to become independent of experience? The difference is that after some little experience we know what a "whole" is and what a "part" is well enough to see that denying the principle would entail a contradiction. What "water" is, however, our experience does not reveal to us quite so perfectly.

David Hume speaks of a knowledge that "arises entirely from experience, when we find that any particular objects are constantly conjoined with each other."(52) He says that "All the laws of nature, and all the operations of bodies without exception, are known only by experience."(53) This is not in fact as universally true as Hume would have us think, but it is true about the vast majority of modern scientific results. Poincaré, too, said that every generalization is a hypothesis. That is not true without qualification (the statement itself is a generalization!), but it is true of most of the generalizations made in science.(54) That every change is between opposites is not a hypothesis, but something self-evidently and necessarily true without exception; that the color red is always associated with such and such a frequency is a generalization we make based on repeated experience, and nothing more.

Yet again we see a complementarity between natural science and natural philosophy. Philosophy has a greater kind of certainty in its principles and conclusions, but at the cost of being quite restricted as to what it can investigate by such means. Science has a much greater freedom of inquiry, but at the price of giving up perfect certainty,(55) of assuming a provisional quality, ever revising and adjusting its statements in the light of new evidence.

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Once all these distinctions among the major approaches to studying nature are made, it is possible to ask about the relationships between them. Throughout this article I have contrasted "natural philosophy" with "science," in keeping with the common way of speaking today. This way of speaking, however, has the disadvantage of implying that we are speaking of two disciplines quite independent of each other.

The truth is that what we call "science" today is only a continuation of what we call "natural philosophy," and it certainly cannot replace it. A particular knowledge cannot replace a more general knowledge, both because it is a different knowledge(56) and because it is less certain. A knowledge based on confined experiences cannot replace one based solely on universal experience, because any advanced knowledge based on confined experiences depends on human faith, and is in that measure less certain. A knowledge based on unreflective experience alone cannot replace a knowledge based on reflective experience, because many of the things known by reflective experience cannot be known in any other way. A knowledge based on artificial experiences, such as experiments, cannot replace a knowledge based on natural experience, because even in experiments we rely upon the use of our senses in the ordinary way to read our instruments. A quantitative knowledge cannot replace a qualitative one because nature is more than its quantitative aspects, and there are many things in the natural world that can be known but not by measurement, such as substance, nature, and purpose. Knowledge based on hypotheses cannot replace knowledge based on self-evident principles, because it is less certain.

People at each end of the study of nature have tried to emancipate themselves from those at the other end. Philosophers,

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seeking certainty, the ease of the armchair, and perhaps fearing mathematics, have restricted themselves to investigating questions about nature accessible from common experience, inward reflection, and self-evident generalities--or they have entirely given up talking about nature. As I noted at the beginning of this article, this is not a particularly philosophical disposition; it leaves us with vague certainties, which cannot be enough for any philosophic spirit.

Scientists, on the other hand, often have a distaste for anything vague, however certain it may be. They demand the clarity of mathematical conceptions and procedural definitions in all things.(57) They will not approach nature through self-evident principles, since these tend to be vague generalities, nor through reflective experience, since although it is very certain it is correspondingly imprecise and obscure.(58) Often, too, scientists suffer from a confusion of certainty with distinctness in our knowledge, unwittingly following Descartes. Those who mis-takenly identify these will tend to reject the more philosophical study of nature as uncertain because it is vague, when in fact that is exactly why it is certain, and they will embrace the more scientific study of it as certain because it is particular and detailed, when in fact that is exactly why it is uncertain. Many a scientist, too, loves his freedom too much to study nature in the more philosophic way. Those methods restrict him too much; if he takes the initiative and forces nature to answer his questions experimentally, he is allowed to ask about anything as long as he can devise a way to test his predictions.

We should not condemn anyone who chooses to focus on one or another method for the study of nature. Choice is inevitable.

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It is impossible for one person to become proficient in both the "scientific" and the "philosophic" ways of approaching nature without at least one of these suffering to some extent.(59) We may become expert in one, amateur in the other, but an expert in both is more an ideal than a reality. To become expert in one field of science is typically a lifetime achievement. This is no less true of becoming expert in the philosophy of nature. More than ever before, we are becoming conscious of how subject we are to time: vita brevis, scientia longa. Temperament and personal preferences and educational experience, too, might suit one person more than another for the philosophic or the scientific study of nature. I take issue only with those who say that only one of these approaches yields legitimate and worthwhile knowledge, or that they are independent of each other and can safely ignore each other, or that they constitute separate disciplines. To distinguish the methods by which nature can be known is a good thing. But to segregate those using different methods is to insist on unscientific philosophy and unphilosophical science. This would be the dismemberment of the knowledge of nature.

The philosophical study of nature depends on science for completion, to bring our more general knowledge into concrete focus, and to open lines of questioning that are bound to come up for the philosopher, but that he cannot answer from his armchair. "What is time?" asks the philosopher. Even presuming that his answer is correct when he says it is a kind of number of motion, the next question must be "Is there one motion whose number is the time?" His own line of questioning draws him naturally into science. "What is the soul?" he asks on another occasion. Even presuming that his answer is correct when he says it is the substantial form of a natural body equipped with organs, he must wonder of what kind of organic body is the human soul the substantial form. Once more, he is drawn into science. In defining

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"motion," he makes mention of "place," and in defining "place" he must talk about a frame of reference and once more he is entering the realm of science, in which we ask about the size and shape of the universe we inhabit.

The sciences in turn depend on the philosophical study of nature. The natural philosopher does not achieve a distinct knowledge of things in the sense that he descends to very particular kinds of things, but he does achieve a distinct knowledge of the very general things he studies. He defines them. What is a living thing? This question is answerable in a definitive (if vague) way only by the philosophical study of nature. A biologist might have a great career without ever attending seriously to this question, without ever availing himself of the methods of the philosopher, but then he is indifferent to what it is his own work is supposed to be illuminating. Science also cannot understand its own methods, or explain why they are appropriate or necessary, without turning to the philosophy of nature. A scientist who tries to define science is not practicing "science" in the modern sense of the word, but he is certainly philosophizing. Even a scientist who contends that only the methods called "scientific" today are appropriate for studying nature is in fact making a statement about nature without using those methods. It is impossible to know what one means by "science," in any sense of the term, without going back to a reflective experience of knowing things scientifically. And this is what many call a "philosophical" approach. Science also depends on the philosophy of nature for stability and guidance. To illustrate: if the philosopher of nature can demonstrate that understanding and willing are not acts of bodily organs, then this should be taken into account in neuroscientific research.

Which method affords a superior knowledge of nature? A knowledge of natural things, once it has progressed by natural stages to the level of particularity in science, is superior. It is more detailed, distinct, unfettered in its scope of inquiry. But this is assuming a scientist who accepts and applies the givens of reflective experience, and general principles such as "nature acts

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for an end." A science isolated in a world of external phenomena, despite its astonishing detail, remains largely on the outside of things, making it a somewhat superficial knowledge. If we compare the beginning of the study of nature, the more "philosophic" part, to the more detailed "scientific" parts that should be its continuation but are instead pursued in isolation from it,(60) the beginning is a better knowledge. For in that beginning, in the more philosophic approach, we obtain a knowledge of some things nobler and more important to us than any studied in science, such as the human soul, and the difference between living and nonliving things and natural and artificial things. Though vague, natural philosophy is certain, and it is a living science, as opposed to the necessarily lifeless world of "objective" biology,(61) to say nothing of physics and chemistry.

In terms of practical fruit, the particular sciences can make technological products possible independently of natural philosophy. Natural philosophy either has no such fruit at all, or very little. But science is a blind guide to the much more important practical questions about how we should live, and in particular about how we should use science and technology. Science, in the restricted modern sense, prescinds from the good,(62) just as mathematics does, and by ignoring our inward

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experience of things, such as our own desire, without which a knowledge of the good is impossible. Accordingly, natural philosophy can ground ethics, studying the nature of man's soul and showing that nature acts for an end, whereas our modern "science," divorced from the philosophy of nature, is worthless in that regard.

Natural philosophy is also a better preparation for the study of truths about God. In pursuing these truths philosophically, we understand more what God is not than what he is. The via negativa, however, is much more fruitful the more general are the things we deny of God. "God is not a carbon atom" is not very instructive, whereas "God is not a body" is very illuminating. We cannot succeed in making these negations, though, unless we know quite distinctly what it is we are negating. We must know, to the point of being able to define them, what "body," "motion," and "matter" are. This is the work of the philosophy of nature.

Aristotle recognized the need for a more and more detailed experience of nature:

Lack of experience diminishes our power of taking a comprehensive view of the admitted facts. Hence those who dwell in intimate association with nature and its phenomena grow more and more able to formulate, as the foundations of their theories, principles such as to admit of a wide and coherent development: while those whom devotion to abstract discussions has rendered unobservant of the facts are too ready to dogmatize on the basis of a few observations. The rival treatments of the subject now before us will serve to illustrate how great is the difference between a "scientific" and a "dialectical" method of inquiry.(63)

Aristotle recognized, too, the scientist's need for hypotheses testable by experiment and observation. Speaking of the followers of Empedocles and Democritus, he says:

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their explanation of the phenomena is not consistent with the phenomena. And the reason is that their ultimate principles are wrongly assumed: they had certain predetermined views, and were resolved to bring everything into line with them. . . . But they, owing to their love for their principles, fall into the attitude of men who undertake the defence of a position in argument. In the confidence that the principles are true they are ready to accept any consequence of their application. As though some principles did not require to be judged from their results, and particularly from their final issue! And that issue, which in the case of productive knowledge is the product, in the knowledge of nature is the phenomena always and properly given by perception.(64)

Aristotle was also quite aware of the need for applying mathematics and measurement to the study of natural things.(65) So why isn't he credited as the father of "science," even as we understand it today? Why does its founding wait until Galileo? Certainly Galileo was among the first to show the world just how powerful these methods are, and how quickly they become necessary when we investigate nature. Also, we happen to agree with Galileo's Copernican hypothesis, and not with the geocentric hypothesis of Aristotle. Moreover, many "scholastic" teachers in the time of Galileo contented themselves with being disciples of Aristotle, measuring their knowledge by conformity to his words rather than to reality. These false representatives gave Aristotle his undeserved reputation as an armchair philosopher who, like themselves, presumably would have refused to look through Galileo's telescope. As with any philosophic spirit, this is impossible to believe about a man who reflected that

The scanty conceptions to which we can attain of celestial things give us, from their excellence, more pleasure than all our knowledge of the world in which we live; just as a half glimpse of persons that we love is more delightful than an accurate view of other things.(66)


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We are right to laugh at the legendary philosophers with a predilection for the abstract who, out of their loyalty to obsolete theories, refused to look at the world through a telescope. One hopes the day might arrive when we will find equally amusing the scientific type who refuses to remember what the world looks like without one.

1. De Caelo 2.12.291b25, J. L. Stocks translation, from The Complete Works of Aristotle, ed. Jonathan Barnes (repr.; Princeton, N.J.: Princeton University Press, 1995). All quotations of Aristotle will be drawn from this edition. In his Meteorology, Aristotle remarks that "We consider a satisfactory explanation of phenomena inaccessible to observation to have been given when our account of them is free from impossibilities" (1.7.344a5, E. W. Webster translation).

2. Stephen Hawking notes this concession of the philosophers: "Up to now, most scientists have been too occupied with the development of new theories that describe what the universe is to ask the question why. On the other hand, the people whose business it is to ask why, the philosophers, have not been able to keep up with the advance of scientific theories. In the eighteenth century, philosophers considered the whole of human knowledge, including science, to be their field and discussed questions such as: Did the universe have a beginning? However, in the nineteenth and twentieth centuries, science became too technical and mathematical for the philosophers, or anyone else except a few specialists. Philosophers reduced the scope of their inquiries so much that Wittgenstein, possibly the most famous philosopher of this century, said, The sole remaining task for philosophy is the analysis of language. What a comedown from the great tradition of philosophy from Aristotle to Kant!" (Stephen Hawking, A Brief History of Time [New York: Bantam Books, 1990], 174-75).

3. The very word "scientist," it seems, was not coined in English until 1834. See the Oxford English Dictionary, 2d edition, ed. J. A. Simpson and E. S. C. Weiner (Oxford: Clarendon Press, 1989).

4.  "For it is owing to their wonder that men both now begin and at first began to philosophize; they wondered originally at the obvious difficulties, then advanced little by little and stated difficulties about the greater matters, e.g. about the phenomena of the moon and those of the sun and of the stars, and about the genesis of the universe" (Aristotle, Metaphysics, 1.2.982b10-15; W. D. Ross translation).

5.  Thus Thomas Aquinas points out that those who use a mathematical method to study nature are nonetheless more natural scientists than mathematicians, because they use mathematics for the sake of understanding something about nature, not something about mathematical things. See II Phys., lect. 3, n. 336 (In octo libros de Physico auditu sive Physicorum Aristotelis Commentaria, ed. P. Fr. Angeli and M. Pirotta, O.P. [Naples: M. d'Auria Editore Pontificio, 1953], p. 82). The naturalist who applies mathematics to nature considers every term, such as "straight," "triangle," "circle," in concreto, thinking of each as existing in some kind of sensible matter. This difference in the mode of defining is the crucial difference between mathematics and natural science. One defines with, the other without, sensible matter. This is not a difference of method, but a difference in what they are studying, an essential difference in the intelligibility of their subject matters. See Aquinas, In Boet. de Trin., q. 5 ("De divisione speculativae scientiae"), a. 1.

6.None of this constitutes an objection against distinguishing parts of one science as a convenience for the division of labor.

7. Aristotle, Parts of Animals, 1.5.645a5-10 (William Ogle translation).

8.  "Mathematics is not a science from our point of view, in the sense that it is not a natural science. The test of its validity is not experiment" (Richard P. Feynman, Six Easy Pieces, ed. Robert B. Leighton and Matthew Sands [repr.; Reading, Mass.: Helix Books, Addison-Wesley, 1995], 47).

9. "Scientist" is more concrete than "science," and so it is natural for people to define "science" by what is common to all the people called "scientists." If those who call themselves scientists, however, arbitrarily restrict themselves to using certain methods to study nature when other legitimate ones exist, the "science of nature" will end up with an artificially restrictive definition.

10. This is one of the reasons that it is difficult to defend the idea of a university, today, where science and philosophy departments are supposed to coexist peacefully, and even cooperate. "The presumption is that nature is every bit of what science can reveal, but a great deal more besides, and that some of this, too, can be known" (Charles de Koninck, "The Moral Responsibilities of the Scientist," Laval Théologique et Philosophique 6 [1950]: 356).

11.  I make no claim to exhaustiveness, but only to bringing out the most fundamental oppositions which bear on the distinction between "science" and "the philosophy of nature" in the modern and restricted senses of these terms.

12.  See Aristotle, Physics, 7.7. I cite Aristotle here not as an authority, but as an example of the way of studying natural things that is so commonly distinguished against "science."

13.  See ibid., 1.4.187b7.

14. See Aristotle, De Caelo, 1.5-7.

15.  See Aristotle, Physics, 4.11.219b2 ff.

16.  The natural philosopher can talk about some very particular things, but not in concrete detail, as it were. The human soul, for example, is about as specific a thing as one could hope to find: it is the form of a most specific species of things, namely, man. What enables the philosopher to speak about so specific a thing, however, is his use of his interior experience of being a man, which does not enable him to speak in detail about the body of which this soul is the form. Details about the human body take us immediately into the realm of science.

17.  "The laws of physics can acquire this minuteness of detail only by sacrificing something of the fixed and absolute certainty of common-sense laws. There is a sort of balance between precision and certainty: one cannot be increased except to the detriment of the other" (Pierre Duhem, The Aim and Structure of Physical Theory [repr.; New York: Atheneum, 1974], 178-79).

18. Scientists make this distinction, too. Werner Heisenberg, for example, says, "Since the time of Galileo the fundamental method made it possible to pass from general experience to specific experience, to single out characteristic events in nature from which its 'laws' could be studied more directly than from general experience" (Werner Heisenberg, Physics and Philosophy [New York: Harper & Row, 1962], 149).

19. Niels Bohr says that the aim of every physical experiment is "to gain knowledge under reproducible and communicable conditions" (Niels Bohr, Atomic Physics and Human Knowledge [New York: John Wiley and Sons, Inc., 1958], 37).

20.  "The goal of science is to augment and order our experience" (ibid., 88).

21. As Einstein put it, "The whole of science is nothing more than a refinement of everyday thinking. . . . Scientific thought is a development of pre-scientific thought" (Albert Einstein, Out of My Later Years [repr.; Westport, Conn.: Greenwood Press, 1970], 59).

22.  It is this meaning of "common sense" that Carl F. von Weizsäcker had in mind when he said "Aristotle wanted to preserve nature, to save the phenomena; his fault was that he made too much use of common sense. Galileo dissects nature, teaches us to produce new phenomena; and to strike against common sense with the help of mathematics" (Carl F. von Weizsäcker, The Relevance of Science, Gifford Lectures, 1959-60 [London: Collins, 1964], 104).

23. That there should be real and living things which do not exist in place and time and which have no shape or size runs more contrary to "common sense" than anything in the whole of science, and yet this is a conclusion of perennial philosophy. Whether one accepts the arguments or not, no one can deny that Aristotle was philosophizing when he arrived at the conclusion that there are indeed separated substances.

24. J. Henri Fabre dispelled many an anthropomorphic interpretation of insect behavior. In chapter 10 of The Hunting Wasps, entitled "The Ignorance of Instinct," for example, he lays out several experiments in which different kinds of Sphex, seeming to know what they are doing, are proved to have no idea what they are doing. See J. Henri Fabre, The Insect World of J. Henri Fabre, ed. Edwin Way Teale, trans. Alexander Teixeira de Mattos (Boston: Beacon Press, 1991), 55ff.

25.  This is the idea behind distinguishing between "philosophical" psychology and "experimental" psychology. If these are conceived as two parts of one science which must avail itself of many methods, I cannot object to the distinction. I object only when they are conceived as entirely different and independent studies.

26. "Scientific investigation does not lead to knowledge of the intrinsic nature of things" (A. S. Eddington, The Nature of the Physical World, The Gifford Lectures 1927 [New York: The Macmillan Company, 1930], 303). "The Victorian physicist felt that he knew just what he was talking about when he used such terms as matter and atoms. Atoms were "tiny billiard balls," a crisp statement that was supposed to tell you all about their nature in a way which could never be achieved for transcendental things like consciousness, beauty or humour. But now we realise that science has nothing to say as to the intrinsic nature of the atom. The physical atom is, like everything else in physics, a schedule of pointer readings. The schedule is, we agree, attached to some unknown background. . . . We have dismissed all preconception as to the background of our pointer readings, and for the most part we can discover nothing as to its nature. But in one case--namely, for the pointer readings of my own brain--I have an insight which is not limited to the evidence of the pointer readings. That insight shows that they are attached to a background of consciousness" (ibid., 259). C. F. von Weizsäcker also points out that the things we know by reflective experience are not approachable by the methods to which scientists restrict themselves: "Light of 6000 Å wavelength reaches my eye. From the retina, a chemico-electrical stimulus passes through the optical nerve into the brain where it sets off another stimulus of certain motor nerves, and out of my mouth come the words: The apple is red. Nowhere in this description of the process, complete though it is, has any mention been made that I have had the color perception red. Of sense perception, nothing was said" (C. F. von Weizsäcker, The History of Nature [Chicago: University of Chicago Press, 1949], 142-43).

27.  The Insect World of J. Henri Fabre, 327. Einstein makes a similar observation; in contrast to the detective, he says, "The scientist must, at least in part, commit his own crime, as well as carry out the investigation" (Albert Einstein and Leopold Infeld, Evolution of Physics: The Growth of Ideas from Early Concepts to Relativity and Quanta [New York: Simon and Schuster, 1938], 78).

28. Kant mentions these two proportions in his Critique of Pure Reason ("Preface to the Second Edition," trans. Norman Kemp Smith [New York: St. Martin's Press, 1965], 20). He endorses the comparison of the scientist to a judge, but rejects the attitude of being a student toward nature. In other words, like almost everyone after him, Kant rejects the philosophical study of nature, recognizing only the scientific study of it. The half truth in his view is that we should not rest satisfied beginning with whatever nature reveals about itself in things naturally known to us; we should force nature to answer as many other of our questions as we can. It is a mistake, however, to think that this is the only way to study nature.

29. The idea of "listening" to nature might be implied in the title of Aristotle's so-called Physics. As F. M. Cornford notes in his general introduction to his translation of Aristotle's Physics, "The title 'Physics' is misleading, and the reader must expect to find little or nothing that it suggests in the treatise" ("General Introduction," Loeb Classical Library 228 [repr.; Cambridge: Harvard University Press, 1993], xv). The title is FUSIKHS AKROASEWS, which, rendered literally into English, is Of Natural Hearing. The full title is The Eight Books of Natural Hearing, which seems to mean "Hearing about Nature," perhaps because it consists in lecture notes, although it might also mean "Listening to Nature." Some authors of Latin commentaries on the Physics suggest the title means "natural philosophy acquired through hearing," in the sense that one cannot understand the text simply by reading it but has to have it explained, hearing it from a teacher. Whatever the title means, it is certainly true that Aristotle's Physics is more like listening to nature than what a physicist does. The physicist is far less passive, supplementing whatever experience nature happens to provide with carefully planned artificial experiences, outfitting the observation equipment provided by nature with artificial aids, and supplementing the things naturally known to us with carefully chosen hypotheses.

30. The natural philosopher talks about the artificial in order to understand the natural by contrast or by likeness.

31. The natural philosopher occasionally ignores the distinction between natural and artificial, too. The sixth book of Aristotle's Physics is about the properties of motion connected with its continuousness, and most of the statements Aristotle makes about motion in that book are true whether the thing in motion is a fish or a ship. As with science, one of the reasons this treatment of physical things can overlook the distinction between the natural and the artificial is that it is focusing on the quantitative aspects of things.

32.  Physicist Hermann Weyl says that "the scope of the understanding from within appears practically fixed by human nature once for all, and may at most be widened a little by the refinement of language . . . . Understanding, for the very reason that it is concrete and full, lacks the freedom of the 'hollow symbol.' A biology from within as advocated by Woltereck will, I am afraid, be without that never-ending impetus of problems that drives constructive biology on and on" (Hermann Weyl, Philosophy of Mathematics and Natural Science, trans. Olaf Helmer [repr.; New York: Atheneum, 1963], 283-84).

33. "Organ," coming from the Greek word for tool, implies purposefulness. "Appendage" would be a better word for something of which it is denied that nature makes it for the sake of something.

34. Erwin Schrödinger, Mind and Matter (Cambridge: Cambridge University Press, 1959), 90-95. Hermann Weyl also acknowledges that there is another way to understand life: "Scientists would be wrong to ignore the fact that theoretical construction is not the only approach to the phenomena of life; another way, that of understanding from within (interpretation) is open to us. . . . Of myself, of my own acts of perception, thought, volition, feeling and doing, I have a direct knowledge entirely different from the theoretical knowledge that represents the 'parallel' cerebral processes in symbols. This inner awareness of myself is the basis for the understanding of my fellow-men whom I meet and acknowledge as beings of my own kind, with whom I communicate, sometimes so intimately as to share joy and sorrow with them. Even if I do not know of their consciousness in the same manner as of my own, nevertheless my 'interpretative' understanding of it is apprehension of indisputable adequacy. Its illuminating light is directed not only on my fellow men; it also reaches, though with ever increasing dimness and incertitude, deeply into the animal kingdom. Albert Schweitzer is right when he ridicules Kant's narrow opinion that man is capable of compassion, but not of sharing joy with the living creature, by the question, 'Did he never see an ox coming home from the fields drink?' It is idle to disparage this hold on nature 'from within' as anthropomorphic and elevate the objectivity of theoretical construction" (Weyl, Philosophy of Mathematics and Natural Science, 283-84).

35. Or that men differ from animals or computers.

36. This self-imposed seclusion in "objective" experience goes a long way toward explaining many otherwise baffling denials of biologists and psychologists. K. S. Ashley, for example, says "There is not direct knowledge of an experiencing self. . . . The knower as an entity is an unnecessary postulate" (Brain Mechanisms and Conciousness: A Symposium, ed. Edgar D. Adrian, Frederic Brenner, and Herbert H. Jasper [Oxford: Blackwell, 1956], 423-24). Psychologist Gordon Allport remarks that "For two generations, psychologists have tried every conceivable way of accounting for the integration, organization and striving of the human person without having recourse to the postulate of a self" (Gordon W. Allport, Becoming [New Haven: Yale University Press, 1955], 37). Compare this, now, to the following remarks of Thomas Aquinas about the indispensable role of reflective experience: "For it is manifest that this individual man understands: for we would never inquire about the understanding if we did not understand; nor when we inquire about the understanding do we inquire about any other principle than that by which we understand" ("Manifestum est enim quod hic homo singularis intelligit: nunquam enim de intellectu quaeremus, nisi intelligeremus; nec cum quaerimus de intellectu, de alio principio quaerimus, quam de eo quo nos intelligimus" [De Unitate Intellectus, c. 3). "Those things which are in the soul by its essence are known by an experiential knowledge, inasmuch as man experiences intrinsic principles through their acts, as we perceive the will in willing, and life in the operations of life" ("Illa quae sunt per essentiam sui in anima, cognoscuntur experimentali cognitione, inquantum homo experitur per actus principia intrinseca: sicut voluntatem percipimus volendo, et vitam in operibus vitae" [STh I-II, q. 112, a. 5, ad 1]). Commenting on Aristotle's discussion of the two ways in which one knowledge is better than another, Thomas says "This science, that of the soul, has both: because it is certain, for each person experiences this in himself, namely that he has a soul, and that he lives by a soul. And because it is nobler: for the soul is nobler among inferior creatures" ("Haec autem scientia, scilicet de anima, utrumque habet: quia et certa est, hoc enim quilibet experitur in seipso, quod scilicet habeat animam, et quod anima vivificet. Et quia est nobilior: anima enim est nobilior inter inferiores creaturas" [I De Anima, lect. 1]). See also De Verit., q. 10, a. 8.

37. Heraclitus, DK 123; my translation.

38. "It is idle to disparage this hold on nature 'from within' as anthropomorphic" (Weyl, Philosophy of Mathematics and Natural Science, 284).

39."On to something" should not be equated with "true." "In fact, so far as mathematical physics is concerned, practical success is the only guarantee that we are on the right track; but this should not be mistaken for speculative certitude. We do in fact construct highly efficient machines on the basis of shaky theory" (Charles de Koninck, Natural Science as Philosophy [repr.; Québec: Laval University, 1959], 9).

40. "What exact science looks out for is not entities of some particular category, but entities with a metrical aspect" (Eddington, The Nature of the Physical World, 105); "the whole of our physical knowledge is based on measures" (ibid., 152).

41.  Werner Heisenberg says "For our senses the world consists of an infinite variety of things and events, colors and sounds. But in order to understand it we have to introduce some kind of order, and order means to recognize what is equal" (Heisenberg, Physics and Philosophy, 62-63). Richard Feynman expresses himself similarly: "The things with which we concern ourselves in science appear in myriad forms, and with a multitude of attributes. . . . Curiosity demands that we ask questions, that we try to put things together and try to understand this multitude of aspects as perhaps resulting from the action of a relatively small number of elemental things. . . . For example: Is the sand other than the rocks? That is, is the sand perhaps nothing but a great number of very tiny stones? Is the moon a great rock? . . . In this way we try gradually to analyze all things, to put together things which at first sight look different, with the hope that we may be able to reduce the number of different things and thereby understand them better" (Feynman, Six Easy Pieces, 23-24).

42. "Since we must cease to employ familiar concepts, symbols have become the only possible alternative" (Eddington, The Nature of the Physical World, 249). A physicist is better off not using words like "work" or "energy," since these have an ordinary sense which is rather irrelevant to physics. So he uses symbols, labels which have no meaning other than the one he assigns them. A symbol has the added advantage of "standing for" something in such a way that it can be the subject of calculations, unlike a word that designates what a thing is. A farmer might let each pebble stand for one sheep while figuring out how many to keep, how many to sell. In that case, a pebble does not mean "what it is to be a sheep," but stands for "one sheep."

43.  Niels Bohr says that "All account of physical experience is, of course, ultimately based on common language" (Niels Bohr, Essays, 1958-1962, on Atomic Physics and Human Knowledge [New York: Interscience, 1963], 1). Heisenberg says, "One of the most important features of the development and the analysis of modern physics is the experience that the concepts of natural language, vaguely defined as they are, seem to be more stable in the expansion of knowledge than the precise terms of scientific language, derived as an idealization from only limited groups of phenomena. This is in fact not surprising since the concepts of natural language are formed by the immediate connection with reality; they represent reality" (Heisenberg, Physics and Philosophy, 200).

44.  This is not to disagree with Richard Feynman, who says that there is a limit to how much the symbolic statements of physics can be translated into the words of ordinary language minus mathematics (see Richard Feynman, The Character of Physical Law [Cambridge: M.I.T. Press, 1965], 40). The mathematics is essential to explaining the connections between the statements made by the physicist, and therefore much of what he is saying must remain unintelligible to the layman who would not take the time to learn the mathematics. Likewise Eddington says (The Nature of the Physical World, xv) "Science aims at constructing a world which shall be symbolic of the world of commonplace experience. It is not at all necessary that every individual symbol that is used should represent something in common experience or even something explicable in terms of common experience." The symbol, in other words, might represent something very unfamiliar to most people, such as a number obtained by using a sophisticated measuring device and manipulated by a certain mathematical function. Neither the device nor the mathematical function has to be a matter of common experience. But they must be understood ultimately through words, even if words which do not name things in everyone's experience.

45.  "Our knowledge of the external world cannot be divorced from the nature of the appliances with which we have obtained the knowledge. The truth of the law of gravitation cannot be regarded as subsisting apart from the experimental procedure by which we have ascertained its truth" (Eddington, The Nature of the Physical World, 154).

46.  Whatever one thinks of colors, or of the experience of colors, they are some kind of reality of the physical world, even if only of one's own brain. Chemists still use the colors of things to decide what they are or what produced them.

47.  Einstein, The Evolution of Physics, 33.

48.  David Hume, An Enquiry concerning Human Understanding, section 5, part 2, n. 39 (in Great Books of the Western World, ed. L. A. Selby-Bigge [Chicago: Encyclopedia Britannica, Inc., 1952], 466).

49.  "Galileo formulated the problem of determining the velocity of light, but did not solve it. The formulation of a problem is often more essential than its solution, which may be merely a matter of mathematical or experimental skill. To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science" (Einstein, The Evolution of Physics, 95). In this book, Einstein compares the physicist to a detective throughout. There is obviously danger, too, in using the imagination in physics. If the universe is indeed finite but unbounded, for example, any image we form of the universe, other than analogous images of other things, is false.

50. Aristotle, Physics 1.5.188b29-30.

51. Such quasi-universal statements or generalizations entirely dependent upon sense experience are like the primary "hypotheses" of science. Despite their uncertainty, they are perhaps more aptly called givens, data, than hypotheses, since they are not laid down as an explanation for some other phenomenon. Theories consist in further hypotheses, more worthy of the name, which are laid down as explanations of the generalizations based on observation.

52.  Hume, An Enquiry Concerning Human Understanding, section 4, part 1, n. 23 (Selby-Bigge, ed., 459).

53. Ibid.

54. We can be certain in general that there are regularities in nature. But if we have no reason beyond repeated experience to believe that this thing before us is one of those regularities, we cannot be absolutely sure that it does not admit of exceptions.

55. "There are no eternal theories in science. It always happens that some of the facts predicted by a theory are disproved by experiment. . . . Nearly every great advance in science arises from a crisis in the old theory, through an endeavor to find a way out of the difficulties created" (Einstein, The Evolution of Physics, 77).

56. My knowledge that a circle is a "figure" can in some ways be replaced by my knowledge that a circle is a "plane figure contained by a single line equidistant at all points along itself from one point inside called the center," since this is simply a more refined version of the same knowledge. But this relatively particular knowledge of what a circle is cannot replace my more general knowledge of a what a "figure" is, since that is not the same knowledge.

57.  Aristotle noted in his own time that "some people do not listen to a speaker unless he speaks mathematically," but insists that "The minute accuracy of mathematics is not to be demanded in all cases" (Aristotle, Metaphysics 2.3.995a5 and 995a15; W. D. Ross translation).

58.  Cf. the testimony of Bertrand Russell, who says "It seems to me that philosophical investigation, as far as I have experience of it, starts from that curious and unsatisfactory state of mind in which one feels complete certainty without being able to say what one is certain of" (Bertrand Russell, My Philosophical Development [New York: Simon and Schuster, 1959], 133).

59.  Many scientists, such as Werner Heisenberg and Sir Arthur Eddington, have shown considerable gifts in thinking philosophically, and yet they are not the greatest of the natural philosophers. The greatest of the natural philosophers, such as Aquinas and Aristotle, might have made great physicists, but only at the expense of making progress in the more general study of nature.

60.  "The fatal consequences of abandoning all thought of the subject as a whole, to become absorbed and lost in independent investigation of single aspects of it, is illustrated everywhere. The absence of coordination between the sciences, the failure of each to reflect constantly upon the scope and significance of the others have brought all to a state of hollowness" (Charles de Koninck, The Hollow Universe [Québec: Les Presses de L'Université Laval, 1964], 112-13). There is certainly some cooperation amongst the recognized "sciences," such as physics and chemistry and biology, but no one can believe there is any serious cooperation between these sciences and the more general philosophy of nature.

61. "Modern biology, if some of its distinguished representatives are to be believed, dare not call itself true science unless it avoids and ignores all that naturally comes to the minds of ordinary people when they think of familiar animals and plants" (ibid., 79).

62.  The "anthropic principle," whether a sound principle or not, is a fine example of integral science, an approach to nature that does not limit itself to one method or another, but uses whichever approach seems best suited to help us understand the matter at hand. This principle invokes the idea that nature acts for an end, but also attends to the metrical aspects of things so crucial to the physicist. In our modern way of speaking however, we would say that in such cases the physicist is essentially borrowing from the natural philosopher, or in part becoming one himself, and he is stepping outside the methods strictly appropriate to the physicist. How arbitrary this is can be seen by reflecting on the fact that a physicist necessarily borrows from mathematics, which is a discipline that does not even share his subject matter (or go back to sense experience to test its theorems), although it might be applicable to it. If he can thus borrow from the mathematician in his capacity as a physicist, why can he not use the general principles of the philosophy of nature, which is really the general beginning of his own discipline?

63.  Aristotle, On Generation and Corruption 1.2.316a5-13.

64.  Aristotle, De Caelo 3.7.306a5-17. Cf. De Caelo 2.13.293a20-25, about the Pythagoreans: "They further construct another earth in opposition to ours to which they give the name counter-earth. In all this they are not seeking for theories and causes to account for the phenomena, but rather forcing the phenomena and trying to accommodate them to certain theories and opinions of their own." Both quotations are from the J. L. Stocks translation.

65.  See, for example, Aristotle, Posterior Analytics 1.13.

66.  Aristotle, Parts of Animals 1.5.644b32-35; William Ogle translation.

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