[ExI] The Reality of Categories

[Lee Corbin]

Stathis writes

>> Still, I would refuse to believe [the hypothetical alien[ if he
>> said that the lake today has more in common with the rock
>> yesterday than the rock today has in common with the
>> rock of yesterday. (of course, it's possible that he's been
>> artificially created by scientists to mouth absurdities, just
>> like many programs we too have written).
> 
> The point is, it is a different rock from day to day,

Well, that is the whole question!  Should we use the term "the
same rock" and the concept "the same" to refer to two such
highly similar entities?  Clearly we should in daily discourse,
otherwise the funniest movie title ever conceived,
"Dude, Where is My Car?" would lack a point.

I suppose that we realists (as opposed to you nominalists?) 
would affirm that since rocks under normal circumstances
undergo exceedingly little change from day to day, there is
a natural, objective category that's relevant here.

> but for certain practical purposes (which a naturally evolved
> being would know about) it is reasonable to ignore the
> differences and call it the same rock.

Oh yes, just so.

> In the context of personal identity, it is not just the degree of
> similarity that matters. I am roughly as similar to the person I was
> yesterday as I will be to the person who identifies as being me
> tomorrow, and yet I don't anticipate surviving in my yesterday
> incarnation, not even if he exists in a timeless block universe.

So technically speaking, you don't expect to survive this coming
evening?  I'm confused;  I thought that if any memory superset
of you survived, then you survive.  Oh, hmm, I guess you mean
"present incarnation":   you don't expect the present incarnation
to survive the coming night.

Lee