Wednesday, September 10, 2014

Plato (for my Western Philosophy Class)


Plato’s (Socrates’) idea of knowledge as recollection.
2.   Explain
Plato’s Theory of Ideas
3.   Explain
Plato’s “Allegory of the Cave”
4.   What
is a contemporary example of Plato’s Idealism?

and Socrates
Plato was a student of Socrates.
Socrates himself wrote nothing.
The early writings of Plato (dialogues) present Socrates
as questioner and deflator of false claims to knowledge.
In Plato’s middle dialogues Socrates is still there, but
now he is no just asking questions, but he is presenting philosophical ideas.
Kenny – “Common to most of these is a preoccupation with
the famous Theory of Ideas.” (39)

Plato’s (Socrates’) idea of knowledge as recollection.
Kenny, pp. 33-34        
If we are reminded of something we must have been
acquainted with it beforehand.
If we are reminded of absolute equality, we must have
previously encountered it.
We did not encounter it in this present life, using our 5
Here is from Plato’s Phaedo:
Here is a further step,”
said Socrates. “We admit, I suppose, that there is such a thing as
equality--not the equality of stick to stick and stone to stone, and so on, but
something beyond all that and distinct from it--absolute equality. Are we to
admit this or not?”
            “Yes indeed,” said Simmias, “most emphatically.”

            “And do we know what it is?”


“Where did we get our knowledge? Was it not from
the particular examples that we mentioned just now? Was it not from seeing
equal sticks or stones or other equal objects that we got the notion of
equality, although it is something quite distinct from them? Look at it in this
way. Is it not true that equal stones and sticks sometimes, without changing in
themselves, appear equal to one person and unequal to another?”

           “Certainly.”  …..

“So we must have done so, by pure intellect, in a
previous life before we were born – unless, improbably, we imagine that the
knowledge of equality was infused into us at the moment of our birth. If the
argument works for the idea of absolute equality, it works equally for other
similar ideas, such as absolute goodness and absolute beauty.” (34)
In this previous non-physical immaterial life we saw the
The method of Socrates is to get people to remember what
they saw in this previous life. This is the “Socratic method.” By asking a
serious questions people begin to recall the Forms (like, e.g., the question of
The Republic – “What is ‘justice’?”)

Plato’s Theory of Ideas
Democritus is a materialist. Plato is an anti-materialist
Plato is working on the problem of the one and the many.
If there is a set of things that all have the same name,
then there is a non-physical, eternal “Form” or “Idea” of that set.
Socrates, Simmias, and Cebes are all called “men.”
          They have
it in common that all are “men.”
          The word
‘Socrates’ stands for the individual man Socrates.
But in the statement Socrates is a man does the word “man”
stand for anything? Plato’s answer is: Yes.
“Man” here means “humanity,”
not “male.”
For Plato ‘humanity’ means
“The Idea or Form of Man.” (41)
E.g. – say that A, B, and C are all F. (Like Socrates,
Simmias, and Cebes are all men; or like apples, bananas, and oranges are all
          A, B, and
C are all related to a single Idea of F.
          F is the
‘Form’ or ‘Idea’ uniting A, B, and C.
How are Ideas related to ordinary things in the world?
Wherever several things are
F, this is because they participate or imitate a single idea of F.
No Idea is a participant or
imitator of itself.
The Idea of F is F. The Idea
of F is nothing but F.
Nothing but the Idea of F is
really and truly altogether F.
Platonic ‘Ideas’ are not in
space or time, they have no parts and do not change, they are not perceptible
to the senses. (41)
Particulars participate in Ideas.

NOTE: Aristotle called his refutation of Plato’s Theory
of Ideas “the Third Man Argument.” (41)

of the Cave
(P. 49 ff.)
Plato’s line diagram
          Shadows             Creatures            Numbers                       Ideas
                             Opinion                                            Knowledge

Imagine a group of prisoners chained in a cave with their
backs to the entrance.
They are facing shadows of
puppets thrown by a fire against the cave’s inner wall.
The prisoners believe that
the shadows are reality.
          They think physical things are reality.

The prisoners mistake appearance for reality. They think
the things on the wall are real.
If, e.g., the puppeteers
hold up a book, the prisoners see the shadow of the book. They think the shadow
is the reality. They use the word ‘book’ to refer to the shadow. They mistake
appearance for reality.
If they could turn around
they would see the reality, which is the book.
Plato’s point is: the general terms of our language [like “humanity”] are not
“names” of the physical objects that we can see. They are actually names of
things that we cannot see, things that we can only grasp with the mind.

is a contemporary example of Plato’s Idealism?

Mathematical Platonism.

See, e.g., University of
Toronto philosopher James Robert Brown's 
of Mathematics: A Contemporary Introduction to the World of Proofs and Pictures
. Chapter Two is entitled

This was the chapter that "disturbed" Massimo Pigliucci. (See 

Pigliucci writes:

"If one ‘goes Platonic’ with math [note: a number of mathematicians are
mathematical Platonists], one has to face several important philosophical
consequences, perhaps the major one being that the notion of physicalism goes
out the window. Physicalism is the position that the only things that exist are
those that have physical extension [ie, take up space] – and last time I
checked, the idea of circle, or Fermat’s theorem, did not have physical
extension. It is true that physicalism is now a sophisticated doctrine that
includes not just material objects and energy, but also, for instance, physical
forces and information. But it isn’t immediately obvious to me that
mathematical objects neatly fall into even an extended physicalist ontology.
And that definitely gives me pause to ponder."

The logic of mathematical Platonism runs like this. Brown cites the connection
between Platonism and semantic theory. He writes:

"Let us suppose the sentence 'Mary loves ice cream' is true. What makes it
so? In answering such  question we'd say 'Mary' refers to the person Mary,
'ice cream' to the substance, and 'love' refers to a particular relation which
holds between Mary and ice cream. It follows rather trivially from this that
Mary exists. If she didn't, then 'Mary loves ice cream' couldn't be true, any
more than 'Phlogiston is released on burning' could be true when phlogiston
does not exist.

The same semantical considerations imply Platonism. Consider the following true
sentences: '7+5 = 12', and '7 
>12'. Both of these require
the number 7 to exist, otherwise the sentences would be false. In standard
semantics the objects denoted by singular terms in true sentences ('Mary', '7')
exist. Consequently, mathematical objects do exist." (Brown, 13)

So, the number '7', and 'pi', and you-number-it, exist. But where? Surely, not
in physical reality. I just hit the number 7 key on my keyboard. The number 7
key exists physically. But I won't be hitting the number 7 anytime in the

So Brown states: "Mathematical objects are outside space and time."
(Ib.) They are non-physical, abstract objects with ontological status.