Presentation on theme: "Physics, Book II. (1) Ch. 1 discusses the meaning of ‘nature’ (2) Ch. 2 discusses the difference between physics and mathematics. (3) Ch’s 3-7 discuss."— Presentation transcript:
Physics, Book II
(1) Ch. 1 discusses the meaning of ‘nature’ (2) Ch. 2 discusses the difference between physics and mathematics. (3) Ch’s 3-7 discuss the nature of cause divided cause into four different types. (4) Ch’s 8-9 discuss more completely the notion of teleological nature. In this Bk., Aristotle shows clearly a central way in which he differs from Plato and from materialistic pre-Socratics like Democritus.
“animals and their parts, plants, and the simple bodies, such as earth, fire, air, and water” (192b 7-9). Genus-species definition. How do natural things differ from artifacts? Natural objects have a “innate impulse to change” or contains “within itself … a principle of motion” (192b 14-15) whereas artifacts don’t. E.g., “traveling upward belongs to fire” (192b36)
Consider the views of one’s predecessors and look for a synthesis of their views. This is what Aristotle does next by considering the views of ‘nature’ or substance provided by (some of) the pres-Socratics and by Plato. He then tries to show how they are both wrong, though each contains a part of the truth. His synthesis of their positions gets, he thinks, at the truth of the issue.
“Some people think that the nature and substance of a natural thing is the primary constituent present in it, having no order in its own right, so that the nature of the bed… would be the wood [out of which it’s made, or the atoms for Democritus]” (193a10-11). This, then, is one way we speak of a nature: as the primary matter that is a subject for each thing that has within itself a principle of motion and change” (193a 29-30). This is the doctrine of materialism: that the reality of something is in its matter, whatever particular theory you have about the basic matter/substance: e.g., water for Thales, air, earth, fire and water for Empedocles, or atoms for Democritus.
In another way the nature is in the shape, i.e. the form in accordance with the account (193a32-33). This is the Theory of Forms by Plato. The “account” is the definition of a thing, which is its Form.
The Pre-Socratics are wrong because unformed matter is only potentially something (a bed, or a statue), not the actual thing itself. To change something from a potential to actuality, you must give it shape or form. So, “the form is the nature more than the matter is. For something is called when it is actually so, more than when it is only potentially so” (193b8-9).
But Plato is wrong too since it is not just form that counts. Math vs. physics Both deal with “surfaces, solids, lengths, and points” but “the mathematician is not concerned with them insofar as each is the limit of a natural body” (193b 25, 33). That is, in math, it is okay to treat things as pure form (You don’t, e.g., have to count actual objects when using numbers), but you can’t do that in physics.
In physics, e.g., a curve will be the curve of some material, physical body. Plato’s mistake, then, was to treat physics as math. For odd and even, straight and curved, and also number, line, and point do not involve motion, whereas flesh, bones, and man do – we speak of them as we speak of the snub nose, not as we speak of the curved” (194a 4-6).
Substance – the most basic reality – is any particular combination of form and matter: this woman, that cat, this nose. Arguments? Analogy to crafts (which he says imitates nature). In crafts we must have knowledge of both form and matter; e.g., the doctor must know both the parts of the body and what the parts of for and how they interact.
We need to know the causes of something in order to understand it. (1) the material cause. “That from which, as a is present in it … -- for instance, the bronze … is the cause of the statue” (194b 24-25). (2) formal cause. The account that is the essence of the thing. (3) efficient cause. “the primary principle of change or stability.” Who or what formed the material; e.g., “the father is the [efficent] cause of the child” (194b ). (4) final cause. “something’s end – i.e. what is it for - - … as health is the cause of walking” (194b 34-35).
Material cause: bronze (or atoms, etc.) Formal cause: its Zeus like shape. Efficient cause: me Formal cause: to honour Zeus. Note that the final cause is what makes Aristotle’s position teleological. According to him, everything has a final cause, which means it has an end or a purpose.
Problems: If they exist in a certain way, then either not all events are caused or not all events have a final cause. Luck: Man at the market example 196a3-10. His going to the market is caused (in all 4 senses) but his reason for going (to buy things) is unrelated to finding someone there who owes him money and repays. This repayment, though, is also caused. So luck, then, is an intersection of causal chains with a fortunate outcome. Luck is only, then, an “incidental” or “coincidental” cause. Luck involves intentional behaviour and hence is only possible with respect to entities (like people) who are capable of intentional action.
Luck and chance can not be something that happens regularly. Going to the market and finding food there to buy is not luck or chance because that usually or always happens (unlike running into someone who owes you money and repays it). Chance events are broader and do not involve intentional action: “results of luck also result from chance, but not all results of chance result from luck” (197b1). Differentia: capable of fortune and action..
In ch’s 8 & 9 Aristotle considers two theories that oppose his Ch. 8: Empedocles: a Pre-Socratic philosopher who said that the basic substances of the universe are earth, air, fire, and water, controlled by two opposing forces: love (which brings things together) and hate or strife (which tears things apart). Great cycle with love sometimes in control, sometimes hate: it a theory of randomness in a sense) combined with material necessary.
“A puzzle now arises: why not suppose that nature acts not for something or because it is better [as Aristotle proposes with his final cause], but out of necessity?” (198b16) Teeth example: Empedocles presents a proto-Darwinian picture of evolution. Lots of combinations occur – when love starts bringing things together. Some combinations are fit for their environment and survive; others are not fit for their environment and become extinct.
(1) The regularity of nature Teeth and other parts “and all natural things come to be as they do either always or usually, whereas no result of luck or chance comes to be either always or usually. (For we do regard frequent winter rain or a summer heat wave, but only summer rain or a winter heat wave, as a result of luck of coincidence” (198b 35ff)
(2) The teleological nature of human action as a model of all natural action E.g., in crafts – making beds, etc. – we must have a view to the end when constructing it. E.g., (simple) animals who build amazingly complex things, like spiders and their webs. Plants moving their leaves toward the sun so that they may grow. This is so even though errors will sometimes occur.
Is the necessity that occurs in nature “unconditional and simple” or conditional/hypothetical? Unconditional necessity: E.g., building a wall (like the Dingwall). We must follow the laws imposed by the nature of the objects. E.g., heavy things on bottom, lighter things on top. This is different than both Empedocles' and Aristotle’s theories. There is no purpose here.
Though we must adhere to material necessity, things like walls do not come into existence because of that, but, rather, for a purpose. Hence, the necessity is conditional: If I choose to build a wall, then I must follow the rules of material necessity. Nature is like craft. The matter must be there because the form requires it, not vice versa.