Summary: Physics (page 3)
Luck is happy chance.
It is impossible for the cause by accident (chance) to be prior to the cause by itself (intellect or nature):It is necessary for intellect and nature to be the [first] causes of this universe
1 (prior to chance).
Since nature has been defined by Aristotle as principle of motion and stability
2, then unmoved things no longer fall under nature
3.
There is finality in nature:
If it is by nature and with a view to an end that the swallow makes its nest, [...] it is manifest that such a cause exists in things that happen by nature 4.
Monsters (deformed children, etc.) are a further proof of this: Monsters are errors of that which comes about with a view to an end
5.
Book III
What is movement? This is a question of interest to the physicist, since nature, the object of his study, is a principle of motion.
An object in motion is a mobile, and that which causes its motion is a motor: The motor is motor of the mobile and the mobile mobile under the action of the motor
6.
Since there is no motion outside of things, there are as many species of motion as of being
7.
Thus, the movement of the alterable is alteration, that of the increasable is growth, that of the generable and perishable is generation and perishing.
Aristotle uses the notion of entelechy to define movement. Certain beings do not exist in act, here and now, but can exist potentially. Thus, the machine that a scientist is developing does not yet exist in act, but exists in potential, in his calculations.
Aristotle calls entelechy the fact of passing from potency to act. In other words, a being is in entelechy when it reaches its proper end.
We can define movement by this notion of entelechy. Indeed, the entelechy of the being in potency, as such, is movement
8.
Let us take an example: When the constructible, insofar as we say it to be such, is in entelechy, it is in the process of being constructed, and this is construction
9.
We can also say that the entelechy of what is possible, as possible, it is manifest that it is movement
10.
Aristotle now turns to the study of the infinite. This is because the object of study in physics is magnitudes, motion and time, each of which is either finite or infinite. Infinity is therefore also one of the notions it must analyse.
For Pythagoras, infinity is a thing in itself, actually existing in sensible things.
Where does our idea of infinity come from? For Aristotle, it comes from five experiences:
- time (because it is infinite)
- the division of magnitudes
- thanks to infinity, generation and perishing are endless
- the unlimited (nothing is limited if one thing must always be limited in relation to another)
- the infinity of numbers
- the idea of an infinite body
However, the existence in act of infinity entails many impossibilities.
Infinity cannot exist in sensible things, because an infinite thing would occupy an infinite place (yet nowhere do we see such a thing), and on the other hand, the notion of a body designates by definition that which is limited by a surface, therefore that which is finite.
It can therefore only exist by accident. Or again: the infinite exists only potentially, and not in act.
It can be defined negatively: It is that which cannot be browsed
11, or better, it is that which by nature cannot be browsed, but has neither course nor limit
12.
1 ibid. 198a
2 Book II, 192b
3 ibid., 198a
4 ibid. 199a
5 ibid., 199b
6 III, 200b
7 ibid., 201a
8 ibid.
9 ibid., 201a
10 ibid., 201b
11 ibid., 204a
12 ibid.