Re: Coextensive properties?

From: Pierre-Normand Houle (houlepn.nospam_at_attglobal.net)
Date: 10/13/04 

Date: Wed, 13 Oct 2004 10:56:46 -0400

"patty" <pattyNO@SPAMicyberspace.net> wrote in message news:wU2bd.380568$Fg5.217927@attbi_s53...

> "X is a member of class P", or "X has property P" have the exact same
> logical consequences in every sentence that we could write.

Not true. "Red" is a name of a property : the property of being red.
I do not have to define tomatoes to be red. One who already knows
what the property red is can find out whether or not one given tomato
is red or not. But I do not know what the "red" class is. For all I know,
you could have defined it to be the class containing the negative even
numbers, the Empire State Building and the King of Belgium.

Of course, you can define the "red" class to be the class containing
all red things (all the objects having the property of being red) where
being red is thus understood as that which, in the world, makes it the
case that the object belongs to the "red" class as defined. But you can only
do this if you are a realist about properties. You must believe that there is
something in the world, reflectance properties of surfaces, say, that make
it the case that objects are, or aren't, red, independently of what we see
in particular, possibly illusory prone, circumstances.

Quine might say (but I would have to look further into this) that the class
"red" which is useful in science (as a starting point) is the class of objects
x that have in fact prompted, and will in fact prompt, users to
ascent to the proposition "x is red" when they are (have been) visually
presented with them.

> In fact we
> can always replace the one syntax with the other, without disturbing
> the consequences in the slightest. Whatever metaphysical "essence" that
> one *thinks* one is attributing to objects by naming their properties
> certainly does not make any difference to the logical consequences of
> the formulae. It can never make a difference in a prediction. Is that
> not a fact?

It makes differences in modal contexts. You can say : This car might
not have been red (it might have been painted blue instead.) That is
to say : that *very* car might not have had the *very* property red.
But you can not say : This car (which belongs in the "red" class) might
not have belonged to it. That is, you can not say : This *very* car might
not have belonged to that *very* class. That is a logical contradiction.
A definite class could not have had differnent members. That would
necessarily have been a different class. But we hold (not Quine, but
realists about properties) that a definite objects might have had
definite properties contrary to the ones it in fact has.

> I think objecting to properties because people might think they are
> "essences" is a red herring. Avoiding properties because Quine said
> "For science it is classes SI, properties NO", yet not being able to
> state specifically where it makes a difference, is just stupid.

Fortunately, Quine points out differences.