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PHI130 Week 5: Aristotle

Lecture 9: Aristotle's physics

Final week on Greek philosophy. We started with the founders Thales and Phythagoras, then the "real" founder Socrates. Then two weeks on Plato, the first great metaphysician. We looked at Plato's Doctrine of Forms, concerning reality and knowledge; then at his metaphysical theory of love. This week we look at the second great metaphysician: Aristotle. Aristotle spent ten years in Plato's Academy, and Aristotle later started his own school, the Lyceum.

Critique of Plato's doctrine of forms

Aristotle was heavily influenced by Plato, his teacher, but had a different outlook. Aristotle was critical of Plato, and defined metaphysical reality differently. We look at what Aristotle thought "ultimate reality" is, because that's what we're concerned with in "mind, meaning, and metaphysics". 'Mind' concerns knowledge, and 'meaning' is...?

Aristotle's critique of Plato leads directly into his own philosophy. Aristotle has a number of objections to Plato's Doctrine of Forms, the most famous being the "third man" argument:

Aristotle shows the three "beds" from Book X of Plato's Republic all have the same name, thus an unifying concept. Plato draws out the instance (empirical) and class (ideal) concepts from the beds. Aristotle points out that the individual and the classified "bed" each bear the same label. Thus there must be one notion above the classes of beds that gives the beds their name. Then we have the empirical bed, the ideal bed, and the notion comprising each. This latter notion has no ideal itself unless we invoke a fourth notion that is the ideal of the first three notions, and so on, ad infinitum. This infinite regress undermines Plato's notion of a "supreme" "idea". Plato's argument that aims to prove the existence of two worlds can now be seem to "prove" the existence of a multiplicity, or an infinity, of worlds. Thus Plato's argument is fallacious... false... broken... doesn't work. This surely is not what Plato hoped to prove. Aristotle doesn't accept Plato's Doctrine of Forms as being an appropriate way to think about reality. Instead of thinking in terms of dualistic terms of 'material' and 'ideal' Aristotle suggests we think in imminent terms. That is, there are essences and notions, but the truth of what a notional object is should not be divorced of its physicality. That is, objective reality and substantive reality should not be considered as 'separate'. That is, the essence of an object is within each material instance of it, thus 'imminent', which means 'within'. The essence of things is not 'above' material objects, but rather 'within' them. Defined in this way ultimate reality begins to look different, and this new outlook has fundamental implications concerning knowledge.

Substance (ousia) versus ideas and forms (idea and eidos)

  • Substance: ousia in Greek
  • Ideas or Forms (idea or eidos in Greek)

Aristotle does not reject the concept of eidos, he just thinks that it's "placed" somewhere else. Aristotle sees only existing objects, no 'ideal realm'. This does not mean there is not an essence or form of the bed, but the concept of the object is not to be found anywhere but in the object itself. In this sense Aristotle is close to Plato, but he doesn't hold on to the dualistic conception of the 'material' and 'ideal'.

For Aristotle what is ultimately real is "things in themselves", but not taken merely empirically, also in light of its essence.

Then there's a whole bunch of mumbo jumbo where I'm quite sure the lecturer used the wrong words. He conflates 'substance' and 'essence'. I think what he was trying to say (at T~=12:55) was that Aristotle takes the essence of objects as an abstraction of their material realisations. This abstract essence is placed 'within' the material object, rather than in a higher ideal realm where Plato would place such essence. He says it's not the colour, or mass, or specifics of shape that gives the chair its substantial reality, but I'm pretty sure he must have meant its essential reality. Either that, or Aristotle himself was talking smack.

Plato tries to "leave" the world, through mathematics and theory, to find the ultimate reality; whereas Aristotle tries to "go into" the world, and strip out non-essential material accidents (colour, size, etc.) to find the essence of substantial objects. I.e. the essence of a 'chair' divorced from, but within, each substantial chair.

[Ed: I can't help but wonder if I'm just trying to make what Aristotle said true under interpretation. I guess I should probably go and read what he actually said, or, translations of it, at least. I sure hope that what I'm hearing is what he said, though!]

The world is made of substances, not notions. Things are not notions corrupted to become material. Substances, or things themselves, should be seen through their essence and not their accidental properties.

How do we perceive substance? Per Plato, through noisis, through intuition. That is, you have to *see*. You work for 30 or 40 years and then if you're lucky you can see how everything fits one day. [Ed: I'm giving it 10 years. It's The Future already!]

Real knowledge in Aristotle is closely linked to perception, and in that sense is not close to Plato. Perception is held to be insufficient if its not systematic. There is an immediate way of perceiving the world that can be fooled by appearances, so we have to be careful and systematic in developing our view of the world. Aristotle holds science as: the exhaustive and empirical study of real physical things in themselves. This is totally opposed to Plato. The model is no longer mathematical, it becomes an imperfect natural science. The quest is for the nature of 'substance', not 'notion'.

Actuality vs potentiality

Aside: Aristotle is far less literary and more difficult to read than Plato.

To better define substances we look at 'actuality' vs. 'potentiality'.

  • actuality: reality, state of being, action.
  • potentiality: possibility, candidate future.

A man asleep is potentially a man. A man awake is actually a man. That is, able to think. (Ed: uh...]

A man with eyes closed, a potential seer. A man with eyes open, an actual seer. [Ed: nice!]

Actuality is substance. This implies important aspects of substances.

TODO: continue T~=20

Priority of actuality over potentiality

Lecture 10: Aristotle's physics (cont.)

Implications for physics

Towards Descartes: The Galilean challenge


Aristotle, Metaphysics

Aristotle, Metaphysics, Book Theta, sections 6, 7 and 8.

Aristotle, Physics

Aristotle, Physics, II, 3, 194b15-195a3; III, 1, 200b10-201b15.

Shapin, Scientific Revolution

S. Shapin, The scientific revolution and the origins of modern science (University of Chicago Press, 1996), p.14-29

Reading Questions

Aristotle, extract from the Metaphysics

  • What is Aristotle's distinction between actuality and potentiality?
  • What is Aristotle's distinction between an action done for the sake of some end outside itself and true or complete actions?
  • What does Aristotle mean by saying that actuality is prior to potentiality:
    • in formula?
    • In time?
    • In substance?

Aristotle, extract from the Physics

Aristotle identifies four causes, which can be thought of as four ways we might explain why a certain thing is as it is.

  • Give an example of each of Aristotle's four senses of "cause":
    • material cause
    • formal cause
    • cause of change / efficient cause
    • final cause
  • Give examples of the four kinds of motion or change identified by Aristotle:
    • alteration
    • increase and decrease
    • coming to be and passing away
    • locomotion

S. Shapin, extract from The Scientific Revolution

  • Why were Galileo's views a challenge to Aristotelian physics?
  • Why were Galileo's contemporaries unwilling to accept that the sun was 'blemished'?
  • What did Ptolemy's geocentric system have in common with ancient Greek views of nature (such as that expressed in Plato's Timaeus?