The Cave and the Light Read online

  This was a profound shift—not just away from Plato, but away from the whole direction of Greek philosophy since Thales. Aristotle decided that Reality with a capital R is not (for the most part) something ultimately above or behind the world we see and hear and smell and touch. It is that world. What Plato had dismissed as the illusions of the cave, Aristotle set out to prove were the keys to ultimate understanding all along.

  After all, it seems improbable that some all-knowing Divine Mind would spend so much time and energy generating the world around us, from the sun and moon and heavens and man down to the tiniest flowers and fleas, unless that world had some intrinsic significance. That is, unless it contained important truths that man’s reason was only waiting to discover: “We must trust the evidence of the senses rather than theories,” Aristotle says, “and theories as well, as long as their results agree with what is observed.”7

  Aristotle, we must remember, was a doctor’s son. Although he was very young when his father died, his family were longtime members of the medical guild of the Asclepiades. Using one’s eyes and ears and sense of touch to diagnose ailments and complaints, and judge the course of a disease or its cure, was in a sense a family tradition. According to the great Greek doctor Galen,‡ Asclepid families also taught their sons dissection.8

  So those walks along the beach were not idle time. They must have confirmed for Aristotle what he already suspected, that reason must be linked to the power of observation. Reason steps in after, not before, experience; it sorts our observations into meaningful patterns and arrives at a knowledge as certain and exact as anything in Plato’s Forms. Aristotle’s term for this knowledge of the world was episteme, which later Latin commentators translated as scientia, or science.

  Aristotle is the true father of science and scientific method, by which we still mean a methodical process of observation, classification, and discovery.9 In this, Aristotle was his own best student. In the History of Animals, he describes cutting open a chameleon to see what goes on inside; and he gives us a concise but wholly accurate description of the life cycle of the gnat. In his biological writings alone, Aristotle names over 170 species of birds, 169 species of fishes, 66 types of mammals, and 60 types of insects, making him the father of ichthyology and entomology as well as biology. His writings contain references to the internal organs of more than 100 creatures from cows and deer to lizards and frogs, and most in such detail that the dissector could only have been Aristotle himself.10

  He is also the inventor of the language of science. Words like genus and species, hypothesis and analysis, all find their first and still current use in the works of Aristotle. So do the names of the principal physical and natural sciences. With almost unbelievable discipline and energy, Aristotle invented and wrote the pioneering treatises of all the following fields: biology, zoology, gerontology, physics, astronomy, meteorology (meaning the study of meteors and comets), politics, and psychology, not to mention logic and metaphysics.§ He was the first to use the observation that ships sailing out to sea seem to vanish over the horizon hull first, then masts and sails, to draw a far-reaching conclusion: that the earth must be round.11

  But biology always remained for him the model of true science. The observation, collection, and classification of specimens in order to discern how they differ and how they are alike; noting how the same species can show different characteristics based on different stages of maturity and development; above all, the delight in dealing with tangible objects made of flesh, fur, shell, and bone and the firm feel of organic life instead of the disembodied abstract Forms of the Platonists or numbers of the Pythagoreans: These were fundamental to Aristotle’s way of seeing the world and seeking the truth. They have remained fundamental to the scientific outlook right down to today.

  All this observable data, as we would call it, had to be classified and arranged in order to make sense of it. So Aristotle provides the basic analytic principles by which to do it. There are the treatises on logic, the Prior Analytics and Posterior Analytics; the Topics and On Sophistical Refutations, which show us the pitfalls of faulty logic and reasoning; and the On Interpretation and Categories.‖

  There is indeed far more to Aristotle’s philosophy of science, however, than just an impulse for tidy-mindedness—or, in Bertrand Russell’s famous phrase, “a common-sense prejudice pedantically expressed.”12 Aristotle’s bias toward observation and classification also led him to break completely with the concept of Plato’s Forms. He did so not only because they seemed too abstract and logically unwieldy,13 but because they missed certain essential features of reality.

  Take the example of a puppy, a chocolate brown Labrador retriever. For Plato, what makes our puppy real is not the fur we see, the paws we touch, or the wet muzzle we stroke, but his participation in the ideal Form of Puppiness; or perhaps Chocolate Lab Puppiness as opposed to Yellow Lab Puppiness and Black Lab Puppiness, all of which are subsumed under the Form of Labrador Retrieverness, which is in turn a subset of Dogness (not to mention Retrieverness, along with all the other retriever breeds). In other words, all the dogs and puppies we see are only copies of an ideal standard, which defines what and who they are.

  Aristotle says, Look again. Our puppy, Rover, is not just a puppy. He is also essentially something out of which something else will eventually emerge: a mature dog. That mature Labrador retriever is not separate or distinct from Rover: it is Rover, our puppy, at a later stage, in the same way the man is in the boy. Adulthood is the final form into which Rover, and all individuals, will ultimately evolve.

  A Labrador retriever puppy reveals a lot about Aristotle’s theory of nature.

  “Evolution” is not a bad word for the version of nature that Aristotle brings to the philosophical table.14 It is a world in which all things, puppies, men, plants, and animals, are constantly altering and changing, a nature in which all of us emerge from something and grow into something else without losing our identities, either as individuals or as part of a class of individuals (so even if Rover grows up to look nothing like his earlier puppy self, he is still Rover).

  That continuously becoming something is what Aristotle called substance. Every substance for Aristotle is a compound of physical matter with an intelligible structure or form—a collusion of matter and form of which the individual is the point of intersection. All substances in nature come with attributes that appear in this puppy, this horse, this man, but they are attributes that are determined by their final form (for example, there are chocolate Labs and white Labs, but no pink Labs).

  And not just for animate or living beings. Aristotle’s own example is of an artisan forging a bronze sphere. Bronze is the matter, but sphericity is the form, a form imposed by its maker, just as nature imposes its forms on physical matter. For Aristotle, our visible world is not an illusion or a pale imitation of something else. It is substantial in a literal sense: it is real, and therefore worth knowing on its own terms.

  This is a crucial point, which Plato missed in two ways. First, Plato’s theory of knowledge leaves out the possibility of change. Back at the Academy, Aristotle’s teacher constantly stressed that true Reality is by definition changeless and eternal. In fact, Aristotle was able to answer, change is part of what makes the world what it is and what allows form to reach its full potential. There are no mature dogs without puppies; no men and women without boys and girls; and no certain knowledge that doesn’t take those facts into account.

  The puppy as it grows; the house as it is being built; the vase as it is being turned: All show us at different stages distinct attributes that also point to their final form. By analyzing substances, we begin to think about how the potential turns into the actual. In short, the philosopher and scientist deal not with an ideal Reality, but with a constantly evolving reality with a small r. It’s a reality firmly rooted in the here and now, and what we see, hear, and touch.

  Second, Aristotle restores the reality, even the dignity, of the individual. Aristotle’s for
ms, unlike Plato’s Forms, do not exist separately from individuals. They appear only through the individual. We would know nothing about dogs without individual dogs in the world to observe and study; we would know nothing about justice without individual examples to examine and analyze.

  One could say that Aristotle had turned Plato on his head. Instead of the individual being a pale copy of a more real abstract form, the universal is less real (indeed only a copy) of the individual.15 This reversal left Aristotle’s philosophy with a built-in bias in favor of the individual: in science, in metaphysics, in ethics, and later in politics.

  What’s true of substances such as puppies and vases is also true of men and women, with one additional feature: that of the mind. Thinking is as essential to our form and function as barking or swimming is for the dog. However, it also links us to a much higher level of being. Aristotle’s version of Plato’s God is pure nous, or pure thought. The human soul is not; it includes other faculties or powers, like the senses and the passions. But there is still enough nous left to figure out what is going on.

  If Aristotle’s world is the conquest of matter by form, then the study of the world and nature requires figuring how and why this works. Fortunately, as human beings we come with the equipment to do it. Reason allows us to sift through the multitude of matter and tease out the essential forms and functions that give it all life and meaning.

  I go for a walk through the forest near my house, just as Aristotle walked along the beach at Assos. All around me are trees and plants and flowers of bewildering variety and in various stages of growth. Some trees are mere saplings, others lie dead and rotting on the ground. Still others stand towering toward the sky. Some plants are in bloom and others are about to bloom. Insects crawl or fly in all directions. Birds, including ones I’ve never seen before, flit among the branches; other creatures scurry through the dead leaves or slither through the grass. The wind blows as clouds of constantly changing patterns pass overhead.

  This is nature, the real world buzzing and blooming around us. But we are not overwhelmed or intimidated by it. Aristotle teaches us that certain basic principles underlie all this rich variety and all the change and motion, however strange or bizarre. In addition, these principles are not separate or mysterious but embedded in the things themselves, together with their form and function. The world is a system. Our contemporary notion of an “ecosystem” neatly captures this element of interconnectedness of Aristotle’s view of nature, just as our belief in the power of science to unlock that system is its most important offshoot.

  For Aristotle, nature is no insubstantial mystery, just as no system is entirely static. Like the puppy and like us, systems naturally incorporate change. Aristotle’s term for nature’s built-in bias toward change and motion is energeia; he also uses the word dynamis, which translates as “power.” Aristotle’s worldview is dynamic. Everything I see on my forest walk exhibits that dynamis of nature: growing to maturity, struggling to realize its form, pushing to perform its due function, and then dying. All things exist in a matrix of space and time. All things that are and were and will be must appear in that matrix. They surface either here and now, as in the forest or the beach at Assos, or in the past, as causes, or in the future, as results or actualities.

  So instead of Plato’s philosophy of transcendence, in which everything is a reflection or a sign of something higher and more real, Aristotle gives us a philosophy of causation. Everything that is, has been caused to be or made to happen; and when we discover the cause or causes of a thing, we learn what it is supposed to do and be. We “possess unqualified scientific knowledge of a thing,” Aristotle declares in his Posterior Analytics, “when we think that we know the cause on which the fact depends, as the cause of that fact and of no other.”16

  Causes for Aristotle come in clusters of four. In his house at Assos, there was probably an amphora sitting in the corner, waiting for a delivery of wine or olive oil. Aristotle could see that its material cause was the clay from which it was fashioned; that the potter’s wheel and potter’s hands had been its efficient cause; that the shape of an amphora that was standard all across Greece was its formal cause; and the final cause is what the potter had in mind when he created the amphora in the first place.

  The same cluster applied to natural objects, like our puppy Rover. Flesh and fur are the material causes; Rover’s father and mother are the efficient causes; the physical shape of Labrador retrievers is the formal cause; and the final cause for Aristotle is what Labs are intended to do: to serve man in helping to hunt waterfowl and to be a faithful companion. In Aristotle’s science as it persisted down through the Middle Ages, function is always directly related to form and part of a thing’s essence.

  Today, our thinking runs in a very different direction. We would reserve the word cause to only one of the cluster, the efficient cause.17 No one today ventures to suggest that the end or purpose of a thing is somehow its cause; that part of Aristotle’s science of nature has dropped away. We prefer and expect a scientific view that is less teleological and more provisional and open-ended, with telos, or purpose, left to the human creator or the public, or even to chance.

  But Aristotle himself wanted to see all phenomena as part of a great chain of causation that leads inevitably to the one great final cause. He was determined to establish the essential role of a divinity who is the final cause of everything, the one who sets the whole system in motion, the master engineer.

  Aristotle’s term for this God is the Unmoved Mover or Prime Mover, since He presides over everything that changes or moves in the universe, without changing or moving Himself. He alone has already achieved His actuality, or energeia, simply by being. He thinks, and everything moves.

  Aristotle’s God borrows many of the characteristics of Plato’s God.

  He exists outside time and space; He is knowable only through the effects of His rational presence. But He is also more remote. Aristotle’s God is pure Mind, with no material component or even a point of entry for such a component. Because God is perfect, and thinking is the best and most perfect activity, He can think only about Himself. The intrusion of thoughts about His creation and the creatures in it would not only break His concentration, it would overthrow the very principle on which (for Aristotle) His existence depends: His perfection. Aristotle’s God “cannot care for the world; he is not even aware of it.”18

  It is a frigid, not to say theologically barren, point of view that will get some of Aristotle’s Christian admirers in trouble in the Middle Ages. Still later, it is that very frigidity that will appeal to Enlightenment Deists like Voltaire and Thomas Jefferson.19 Aristotle, however, did not care. There is no sign that he had any interest in the notion of a divine providence, as Socrates and Plato did, or in divine rewards and punishments. Even his theory of the soul includes no mention of immortality. Nature, as he says in many passages, does nothing in vain.20 That seems to have been enough for Aristotle. Like many of his modern scientific successors, he showed little concern for what God does, or more precisely, what God thinks.

  Still, even under the big tent, after analyzing God as Unmoved Mover of the universe in the Metaphysics, Aristotle wants us to come back down to individuals as examples of form, and on individuals’ potential form in the future. In Aristotle’s world, what the puppy was, or the amphora (a shapeless lump of clay), matters less than what it does now and what it will become. The same applies to people. If we want to know what a man really is, we need to focus not on where he came from or what he left behind, but on what he can do now and in the future, as part of his own dynamic nature.

  What applies to individual dogs and men can be extended to human beings in general. For Aristotle’s disciples in the eighteenth century such as Adam Smith, it even applies to entire societies. In the Aristotelian mind-set, it is the future that counts, not the past.

  Here we arrive at one of the most crucial differences between Plato and Aristotle, and one of the most important for
the future shape of Western culture. Plato’s philosophy looks constantly backward, to what we were, or what we’ve lost, or to an original of which we are the pale imitation or copy. In that past original, Plato will say, we find the key that unlocks our future. Later that most Platonist of epochs, the Renaissance, would look back to classical antiquity for its model of perfection, just as the Romantics—Platonists almost to a man and woman—would look back to the Middle Ages.

  Aristotle, by contrast, looks steadily forward, to what we can be rather than what we were. His outlook is by its nature optimistic: “The universe and everything in it is developing towards something continually better than what came before,” including ourselves. It is truly a “philosophy of aspiration,” as scholar F. M. Cornford once dubbed it, and for Aristotle the world we make for ourselves continually reflects that constant striving toward improvement. In that sense, Aristotle is the first great advocate of progress—and Plato, creator of the vanished utopia Atlantis, the first great theorist of the idea of decline.21

  This is why Aristotle was prepared to take a second look at the mechanical, practical arts of his day, or what we call technology. All forms of knowledge, he declares in his usual categorical way, are either theoretical, technical, or practical. Pure theory (epistēmē) is concerned only with knowing and understanding, like biology, metaphysics (or “first philosophy”), and theology. Practical knowledge, praxis, has to do with doing. Interestingly, he puts politics and ethics in that category.

  But technē, the third kind of knowledge, has to do with making. Its goal is not understanding but production. The potter at his wheel, the blacksmith at his forge, the shipwright in a Piraeus boatyard, are not interested in discovering some new scientific principle or adding to the sum of human knowledge. The art of making, Aristotle declares, only imitates nature rather than inventing something new. But in Aristotle’s system, this too makes technē a valid, even dignified, form of action, because it involves the systematic use of knowledge in order to advance human action—one could even say to advance human purpose.