Aristotle's 'Metaphysics', Book I, Chp. III

Aristotle begins this chapter with a brief explanation of what he takes to be the four first principles, or causes, of all that exists. The first is a thing's "being or essence" (formal cause), the second a thing's "matter and substratum" (material cause), the third a thing's "source of movement" (efficient cause), and the fourth is a thing's "purpose...and it's good" (final cause). After this brief explanation, Aristotle goes on to explore what philosophers of the past have thought about the first causes of things.

These philosophers seemed only to be concerned with the material cause of things (what they were made of). Most viewed reality simply in these terms: There is one underlying substance of reality, and that substance merely takes on different "affections". Or, even if there were multiple basic substances postulated, all that exists consisted merely in those substances and the various accidential properties they took on. Thus, there was no true coming into and out of being, but merely formal changes in one, or several, essential substances.

The first example of this thinking given is Thales. Thales believed that the underlying substratum of reality consisted in water. The reasons he gave for this were (1) Everything is nourished by water, and (2) the "seeds" of all things are moist. Aristotle notes that this is something the ancients seemed to believe. The ancients said that the parents of "all that has come into being" were Oceanus and Tethys (sea gods and goddesses). In addition, they swore by the river Styx.

Following Thales, there was Anaximenes and Diogenes, who believed air to be the first principle; Hippasus and Heraclitus, who believed it to be fire; Empedocles, who thought there were the four first principles of water, air, fire, and earth; and, finally, Anaxagoras who believed that there were an infinite number of first causes.

Finally, Aristotle critiques what he takes to be the mistakes made by these metaphysicians of bygone days. He essentially says that just because you have explained the material cause (that out of which it is made) of something, doesn't mean you've explained it's efficient cause (the cause of the thing's movement). As he says, "Certainly the substratum does not cause itself to change". Some, to avoid this issue, said that the whole of nature is itself immovable, and that all change is really an illusion (Parmenides would be an example of this). Aristotle, believing that change is real, says that those who believed in several first principles (such as Empedocles), could make more sense of movement. This is because they could claim that it be the nature of one substance (say, fire) to move things, and another (say, air) to be that out of which things are made.

His last comment is that those, such as Anaxagoras, who believed that nature contained Mind (or Nous), were far more rational than those who did not. The reason he gives for this is that Mind could function as the efficient cause of the world's movement and change, and could also be the cause of things attaining to their purpose or good (achieving their "final cause"). This, then, concludes Aristotle's survey of the strengths and weaknesses of his predecessors.