Table of Contents
Book I
At the end of Book I of Aristotle’s Physics, he claims that he has sufficiently argued that there are principles, that he has shown what those principles are, and that he has determined how many of them there are. Why should we care about principles? Because principles are the doors to scientific knowledge. Aristotle draws on his predecessors, who all agree that contraries are principles. Examples of contraries include excess and defect, above and below, before and behind, angular and angle-less, straight and round, and so forth. If contraries come in pairs and contraries are principles, then in the abstract, there are 2 principles. As we observe things in our world, we notice that their properties tend to change between the contraries. Things change from hot to cold, wet to dry, e.t.c and vice versa. The things in which the contraries display their properties and which persist through the change is called the substratum, which is the third principle.
Book II
Book II gives an account of the primary causes. What is a cause? It is that from which a thing comes to be and that from which it persists. In a single paragraph Aristotle summarizes all of them:
“All the causes now mentioned fall into four familiar divisions. The letters are the causes of syllables, the material of artificial products, fire, &c., of bodies, the parts of the whole, and the premises of the conclusion, in the sense of ‘that from which’. Of these pairs the one set are causes in the sense of substratum, e.g. the parts, the other set in the sense of essence-the whole and the combination and the form. But the seed and the doctor and the adviser, and generally the maker, are all sources whence the change or stationariness originates, while the others are causes in the sense of the end or the good of the rest; for ‘that for the sake of which’ means what is best and the end of the things that lead up to it. (Whether we say the ‘good itself’ or the ‘apparent good’ makes no difference.)”
The first set of causes; the ones that define the letters of syllables, the material of artificial products, the parts of the whole, etc.; are those that Aristotle describes as “that from which.” In general, these correspond to form and matter, where matter, for example, the substratum, which we discovered in Book I to be a principle, is also a cause. The third cause comes from “all sources whence change and stationariness originate”; this is the efficient cause. The “that for the sake of which” is called the final cause.
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