[ExI] The Reality of Categories

Lee Corbin lcorbin at rawbw.com
Sun Jul 15 22:45:53 UTC 2007

Stathis writes

> [Lee wrote]

>> Categories exist and are real.  And firmly maintaining that the old
>> oak tree (before it burned down) was *not* the rock in your garden
>> is as ontologically correct as it is to say that the rock in your garden
>> that changed only infinitesimally *is* the same rock as it was yesterday.
> Only because, by convention, we agree that a few atoms missing and a
> very large displacement in space and time are still consistent with
> the term "same rock".

Are you saying that a rock sitting next to a tree have only conventional
differences?  Yes indeed:  quantum fields are all that there is, and we
do not anymore have the Newtonian vacuum of space in which objects
exist. But these *lumps* the the quantum fields are real lumps, and
very distinct.  When you write "by convention, we agree"  you surely
admit that any intelligent evolutionarily derived organism will detect
these same real categories that we do.  Are you a nominalist?

I appreciate your remarks about personal identity below, but this
thread is about something I consider to be even more fundamental,
the ancient squabble between empiricists, realists, nominalists, and

I'm reading a book "How is Quantum Field Theory Possible?"
which makes a strong case that QFT supports and affirms realism.


>And it isn't so straightforward if we decide to
> destroy the rock and then recreate a copy, or a functionally similar
> analogue - whatever that might mean for a rock - as we propose to
> someday do with people.
> The degree of similarity is only contingently related to the question
> of continuity of personal identity. As you have pointed out, it is
> usual to be more concerned about what will happen to me tomorrow than
> what happened to me yesterday, even though my tomorrow self and my
> yesterday self are roughly equivalent in similarity to my today self.

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