Plato: Physics & Ethics



Quotes & Notes

Plato's Own Assessment of the Forms


Undeniability a la Russell

Existence of Universal Forms a necessary condition for meaningful speech.


bottomless pit of nonsense [need to distinguish real v. nominal; elite v. gruesome; or something


If = partaking: whole v. part dilemma

If = resembling: the "third man" argument (due to reification of Forms?)

Transcendence: the knowledge argument

master-slave v. Master-Slave relation

knowledge-known v. Knowledge-Known

1.        "[I]f a man refuses to admit that Forms of things exist or to distinguish a definite Form in every case, he will have nothing on which to fix his thought, so long as he will not allow that each thing has a character which is always the same; and in so doing he will completely destroy the significance of discourse." (135b)

2.        "[If] the thing which is like [must] share with the thing that is like it in one and the same thing ...[and] that in which like things share, so as to be alike, is just the Form …[then] nothing can be like the Form, nor can the Form be like anything. Otherwise a second Form will always make its appearance over and above the first Form; and if that second Form is like anything, yet a third; and there will be no emergence of these fresh forms, if the form is to be like that which partakes of it."



She swallowed the bird to catch the spider that wriggled and wiggled and tickled inside her.  She swallowed the spider to catch the fly, but I don’t know why she swallowed the fly.  Perhaps she’ll die.



1.        Why she swallowed the bird, & spider.

2.        Why she might die.



          Why did she swallow the fly?

Socrates' disenchantment with materialism

Purposes/Reasons v. Causes/Conditions

Mechanistic modes of explanation -- e.g., it broke because it's made of glass" describe how of things happening.

appeal to constituent structures

and antecedent events

Teleological modes of explanation ("I drove to Alma in order to teach") give reasons why things happen.

The Physical World

Sensory images are subjective appearances

Out of which the so called elements are made according to their distinctive Forms (which he conceived to be geometric, like the Pythagoreans)

And from them in turn so-called "material objects" are made according to their forms.

Space is the "Receptacle of Becoming"

we can know there is somewhere for the appearances to really appear

know nothing about space as it is in itself.

No exact science of what changes

1.        “There is surely a very strange and confusion of causes and conditions in all this. It may be said, indeed, that without bones and muscles and the other parts of the body I cannot execute my purposes. But to say . . . that I do as I do because of them, and not from the choice of the best, is a very careless and idle mode of speaking." (Socrates)

2.        "[The Receptacle of Becoming] is everlasting, not admitting destruction; providing a situation for all things that come into being, but itself apprehended without the senses by a sort of bastard reasoning, and hardly an object of belief."

3.        "We must consider in itself the nature of fire and water, air and earth....For to this day no one has explained their generation, but we speak as if men knew what fire and earth and each of the others is, positing them as original principles, elements (as it were, letters) of the universe; whereas one who has ever so little intelligence should not rank them in this analogy even so low as syllables."

4.        “When [God] laid out the heavens he made this image eternal but moving, in accord with numbers – distinct from eternity which is one and at rest.  This moving image is what we call time.”




1.        To have knowledge of Xs or X-kind there must be a Form – their X- ness – that is known.

2.        There is knowledge of Xs (e.g., brave deeds).  

3.        Therefore there is a Form of bravery.


Prologue: the first existence premise of the Knowledge Argument is much more dubious in the case of Ethics than that of Mathematics!

Example: the Form or Nature of Courage (the definition of "courage")

Too narrow proposals (different examples of courage, e.g., that of soldiers rejected.

general proposal -- standing ones ground in dangerous or trying circumstances -- rejected as too broad

would be rash is some circumstances

Courage = a kind of knowledge or wisdom {4} concerning when to stand ones ground in trying circumstances. (And so for all virtues, according to Socrates.)

Pleasure <> The Good: always best to do what's best & not always best to seek pleasure

Estimate of Socrates View: Trumping Egoism

1.        "I was asking about courage and cowardice in general. And I will . . . once more ask, "What is that common quality, which is the same in all these cases, and which is called courage?" (Socrates)

2.        “God is the measure of all things, in a sense far higher than any man, as they say, can ever hope to be.” (Laws)

3.        “And he who would be dear to God, must as far as possible be like Him and such as He is.  Wherefore the temperate man is the friend of God, for he is like Him.” (Laws)

4.        “Courage is knowing what not to fear.”

5.        “Are there not some which we welcome for their own sakes, and independently of their consequences, as, for example, harmless …enjoyments…?  Is there not also a second class of goods, such as knowledge, sight, health, which are desirable not only in themselves, but also for their results? … And would you not recognize a third class … no one would choose … for their own sakes, but only for the sake of some reward or result which flows from them”