When Socrates refers to the natural sciences he studied, he is undoubtedly referring primarily to the teachings of Democritus and Empedocles. Democritus is famous for positing the existence of atoms, while Empedocles maintained that all matter is composed of the four basic elements: earth, air, fire, and water. Both men used these theories as material explanations for the workings of the universe. That is, their explanations explain how matter moves about in the universe and what forces cause change, somewhat similar to our present concepts of science. For these natural philosophers, things behave in accordance with necessity and chance. By necessity, materials behave in a certain way: for instance, earth always falls, fire rises, water is moist, etc. Sometimes, by chance, two materials will come together and combine, and depending on their relative proportions, they will form different compound substances, such as blood or bone. However, all these explanations only fix the laws governing the behavior of materials, and do not lay out any sort of reason for why they behave as they do. As Socrates notes, they are unable to give an account of complex organisms such as human beings.

Socrates is drawn to Anaxagoras, who seems to provide a teleological explanation rather than simply a material one. Teleological explanation does not exclude material explanation, but rather adds something to it, providing an account that relies on the end goal of an object. Thus, a teleological explanation might take into account the principle that fire rises and then provide a reason for it, explaining why rising should be the end goal of fire. Anaxagoras seems to provide this teleological explanation in the form of his "intelligence." According to his theory, the matter in the universe is all organized in accordance with "intelligence," which remains distinct from the material elements, and places things where they best belong. Much to Socrates' (or rather Plato's) disappointment, however, Anaxagoras does not give any account as to why "intelligence" deems the way things are to be the best possible way. Ultimately, Anaxagoras' explanation is essentially a material explanation, backed by an assertion that "intelligence" approves of this arrangement.

According to Socrates, causation cannot possibly be explained in terms of material explanation. A material cause (for instance, that Socrates is in his cell results from the way his body is situated) only provides those conditions without which the real cause could not operate. The real cause, then, is given by a teleological explanation. A teleological explanation will tell us why things are the way they are rather than simply explaining that they are the way they are. To get a grasp on such an explanation, Socrates turns to theory to solve his problems. His answer to what provides a teleological explanation for things, the Theory of Forms, will be detailed in the next section.

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