Summary: Physics (page 2)

He shows, through an analysis of becoming, that these principles are the opposites (the form, or specificity, and the privation), as well as the substance (the substratum), which passes from one opposite to the other in the course of becoming.

This analysis refutes Parmenides' argument for the impossibility of becoming: change can arise neither from being (for it already is) nor from non-being (for nothing comes from nothing).

Book II

Aristotle distinguishes between two kinds of being: natural beings and artificial objects (technê).

While natural beings appear to possess within themselves a principle of movement and stability ¹, this is not the case for man-made objects: A bed or a cloak, insofar as they are products of art, have no innate tendency to change ².

It is futile to argue with the sceptics about the existence of nature, for it is manifest that there are many such beings ³.

It is even more absurd to attempt to prove this by argument, for to demonstrate what is manifest by means of what is obscure is the mark of a man incapable of distinguishing between what is self-evident and what is not ⁴.

In one sense, the nature of a thing — what is natural in it — is its matter. In another sense, it is its form (or specificity): Nature is said in two ways, in the sense of specificity and matter ⁵.

Aristotle observes that the mathematician differs from the physicist: the former separates accidents that remain connected to the thing, without this entailing any differences and without any error resulting from this separation ⁶.

The Platonists (the partisans of the Ideas ⁷) do the same: They separate the natural beings, which are less separable than the mathematical ones ⁸. This is Plato's error: he abstracts where abstraction is not possible. Only mathematical abstraction is legitimate: Odd or even numbers will exist without movement, but not flesh, bone, or man ⁹.

We must study nature as we would study the "snubness" of the nose: Things of this kind exist neither without matter, nor according to matter ¹⁰.

Since there are two aspects of nature — form and matter — is it then for the same science or for two different ones to know each? ¹¹. The answer is straightforward: since it belongs to the same science to know specificity and matter up to a certain point (health, and the bile and phlegm in which health is found), then it must belong to physics to know both natures ¹².

There is therefore only one science of nature: physics.

Physics seeks the causes of things and aims to explain the world. Yet, we do not consider that we know each thing until we have grasped for each the why (i.e. grasped the first cause) ¹³.

Aristotle recalls the four types of cause: material, formal, efficient, and final.

Can chance be a cause? Aristotle presents the view of those who deny it: nothing ever happens by chance, they argue, for a hidden cause always underlies what appears to happen by chance.

According to Aristotle, chance cannot be the cause of events that occur frequently or necessarily. Yet chance must exist to account for events that occur only rarely.

Finally, just as we distinguish between beings in themselves and beings by accident — as in Aristotle's well-known notions of substance and accident — so too must we distinguish between causes in themselves and accidental causes. Chance is one: Chance is a cause by accident in things that happen with a view to an end ¹⁴.

¹ Book II, 192b
² ibid.
³ ibid., 193a
⁴ ibid.
⁵ ibid., 194a
⁶ ibid., 193b
⁷ ibid.
⁸ ibid., 194a
⁹ ibid.
¹⁰ ibid.
¹¹ ibid.
¹² ibid.
¹³ ibid., 194b
¹⁴ ibid., 197a