Re: Is X a Y?

Nicholas Bostrom (
Mon, 28 Jul 1997 01:54:02 +0000

On Sun, 27 Jul 1997 "Perry E. Metzger" <> Wrote:

>Forget about "reality", I want to know if the Mandelbrot Set
> is different in some very fundamental way from the Virgo Cluster. Can I put
> both things in the same general category, a category that excludes neutral
> electrons, square circles or integer square roots of 7? My suspicion is that
> there is no very fundamental difference between a mathematical object and a
> physical one, but I don't know that for a fact and if I'm wrong I'd like to
> know precisely what the difference is.

What about the old distinction in logical positivism between
propositions true (solely) in virtue of their meaning and
propositions whose truth also depend on how the world is? "There is
an x such that x is the mandelbrot set." would be of the former kind
(analytic); "There is an x such that x is the a galactic cluster
refered to as 'the virgo cluster'." would be of the latter kind

Perhaps the distinction you are after is between objects such
that a proposition asserting that they exist is logically true
(=analytic, i.e. true independently of how the world is) and objects
that don't have this property?

If you reject this distinction, what are your reasons? Are you a

Nicholas Bostrom

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