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Summary: Physics (page 2)

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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) that passes from one of these opposites to the other in becoming.


This analysis removes Parmenides' argument that tries to show the impossibility of becoming: change cannot come from being (for it already is) nor from non-being (for nothing is born from nothing).

Book II

Aristotle distinguishes between two kinds of being: natural being, and man-made being (technĂȘ).

While the former appear to possess in themselves a principle of movement and stability 1, this is not the case with the latter: A bed, a cloak, insofar as they are produced by art, have no innate tendency to change 2.


It is useless to seek to demonstrate, against the sceptics, the existence of nature because it is manifest that there are many such beings 3.

It is all the more absurd to seek to demonstrate this by reasoning because to show manifest things from obscure things is the work of a man incapable of distinguishing between what is self-knowable and what is not self-knowable 4.


In a first sense, the nature of a thing, what is natural in it, is matter. In a second sense, it is also form (or specificity): Nature is said in two ways, in the sense of specificity and matter 5.


The mathematician, he remarks, differs from the physicist, in that the former separates the accidents yet connected in 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 problem: he abstracts where one cannot abstract. Only mathematical abstraction is correct: Odd or even numbers will exist without movement, but not flesh, bone and 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 natures (as form and as matter), is it then for the same science or for two different ones to know each? 11. The answer is simple: 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, indeed it seeks 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: the cause as matter, as form, as principle of motion and as end.


Can chance be a cause? He exposes the idea of those who deny it and think that nothing happens by chance. Indeed, we would always find a hidden cause explaining what seems to happen by chance.

For Aristotle, chance cannot be the cause of what happens frequently, or necessarily. However, chance must exist, to explain things that happen rarely.

Finally, just as we must distinguish between beings by themselves and by accident (this is the famous Aristotelian notions of substance and accident), there is also the cause by itself, and the cause by accident. 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