[MUSIC] Now we turn to Aristotle's natural philosophy, and we will start with a treatise called The Physics, from the Greek phusis for nature. The job of the natural philosopher Aristotle tells us, is to inquire into the principals of change. A basic presupposition of this sort of inquiry is that there really is change, that it's not illusory or incoherent as Parmenides alleged. So Aristotle's first task will be to answer Parmenides challenge. Like his naturalist predecessors, he has to provide an analysis of change which does not imply that there is coming into being from what is not. This is the project he undertakes in book one of the Physics. By the time Aristotle writes this treatise, natural philosophers have been responding to the Parmenidean Challenge for at least a century. Aristotle endorses the general strategy taken by Anaxagoras and Pedicles and the atomists, although he thinks that his own version is superior to theirs for reasons that needn't concern us right now. Aristotle summarizes his version of this strategy in chapter seven of book one. And in chapter eight he explains how it meets Parmenides challenge. I'm going to focus on chapter seven. There he argues that every change has the following principles, an underlying subject and two contraries. For example, when an oak tree grows from a sapling into a mature tree, it changes from small to large. At the beginning of the change, there is a small oak tree. And at the end of the change, there is a large one, which has come to be from the small one. Even though the large oak comes to be from what is not a large oak, it still comes to be from something that is, that is, an oak. So this isn't a case of coming into being from what is not. As long as every change has a persisting subject, which is there at the beginning of the change and still there at the end, then change is not vulnerable to Parmenides' objection. But what about when the oak tree comes into existence? It can't be the underlying subject of this change, so what is? It's not immediately obvious what the persisting subject is in this case, so let's look at a simpler example to get the general idea. When a bronze statue is created in the sculptor's workshop, the statue is not there at the beginning of the process, but the bronze is. The statue comes to be not from nothing but from the bronze. Like the oak tree that persists through the change of growing larger, the bronze persists through the change in which the statue comes into existence. We might say the statue is a rearrangement of some stuff that was there all along. Aristotle calls this pre-existing stuff that is still there in the finished product the matter, the [FOREIGN] of the statue. Before, the statue's matter was not arranged in the shape of a statue, but after, at the end of the change, it is statue shaped. Aristotle says it has acquired the form of a statue, which he will later tell us is what it is to be a statue. Note the platonic pedigree of this notion. Aristotle inherits this platonic tradition and claims that the statue, indeed every substance, can be analyzed into its matter, what it is made of, and its form, what it is. This analysis of change allows Aristotle to meet the Parmenidean challenge, since every substance, every statue, oak tree, dog, horse, and so forth, has as its constituent matter, an underlying subject from which it comes to be. The matter of some substances is pretty easy to identify, as in the case of a bronze statue or a brick wall and so forth. But it's more complicated in the case of natural substances like trees and animals. So what is the matter of the oak tree? We might say, just as the statue is made of bronze, the oak tree is made of branches, bark, and leaves. But the branches, bark, and leaves did not exist before the oak tree did so they can't be the persisting subject underlies the trees coming into being. What about the acorn? Unlike the bark and leaves, it was certainly there at the beginning, but it hasn't persisted through to the end. Rather it's been replaced by the sapling and the mature tree. So the acorn can't be that from which the oak tree comes to be. To identify the underlying stuff out of which the oak tree comes to be, we have to ask what the wood, bark, and leaves are made of. Aristotle accepts the views of his predecessors that earth, air, fire, and water are the ultimate constituents of the natural world, at least in the sublunary region. Up in the celestial spheres, he thinks there is a fifth element, ether, but that needn't concern us here. Now sometimes we don't need to go all the way down to the level of the elements to identify the persisting subject of a coming to be. When we specify the material out of which artifacts, such as furniture and statues come to be, we can identify familiar sorts of stuffs, wood, metal, rock and so forth. But in the case of organisms, we do have to go all the way down to earth, air, fire, and water to identify the persisting subject out of which they come to be. Here's how the story goes in the case of the oak tree. At the microscopic level, the mature tree is made up of elemental earth, air, fire, and water. Most of these constituents were somewhere else when the oak tree was a sapling. Indeed, in the time before the acorn grew and fell from the parent tree, all of them were. But now, all that previously scattered material has been gathered together into the complicated structure that is the oak tree. That stuff or material is the underlying subject of the oak tree's coming into being. And the same is true of you and me and our ultimate constituents. It is out of our material constituents that we have come to be. So this is Aristotle's answer to Parmenides challenge. Every change involves an underlying subject that was there at the beginning, so change does involve coming into being from what is not. Now that's a perfectly good answer to Parmenides. But now it looks like Aristotle has a new problem. Recall his insistence in the categories that substances are the subjects for everything else, and have the distinctive feature of being subjects of change. To get a sense of the problem, consider Socrates and Fido, two of Aristotle's examples of primary substances in the categories. Aristotle emphasizes there the role that Socrates and Fido play as subjects for inherent properties like size and shape. And of universals, such as human, dog, and animal. He also points out that they are subjects of changes. They get bigger. They turn gray. They sit down and stand up or move to a new neighborhood. But the analysis of change in the physics indicates that there is one important change of which Socrates and Fido are not the subject. The change that is their coming into being. As in the case of the oak tree, it is their material constituents, a collection of earth, air, fire and water that are the subject of that change. So this leaves us with two questions. First of all, earth, air, fire and water seem to satisfy the subject test for being a substance. So should we add them to the list of primary substances? Second, if Socrates and Fido are arrangements of Earth, Air, Fire and Water doesn't this make them inherent properties of the material elements? If so, then Socrates and Fido are paradigmatic examples of primary substances in the categories turned out to have a subject in which they adhere. So how can we continue to regard them as primary substances?
