On 17 December 2013 19:06, meekerdb <[email protected]> wrote: > On 12/16/2013 10:02 PM, Jason Resch wrote: > > On Mon, Dec 16, 2013 at 11:56 PM, Stephen Paul King < > [email protected]> wrote: > >> Yes, but why are you being anthropocentric? >> > > I thought that was your position, or at least (observer-centric), in > that numbers only have properties when observed/checked/computed by some > entity somewhere. > > >> If there can exist a physical process that is a bisimulation of the >> computation of the test for primeness, then the primeness is true. >> Otherwise, we are merely guessing, at best. >> > > When we check the primaility of some number N, we may not know whether > or not it is prime. However, eventually we run the computation and find > out either it was, or it wasn't. > > My question to you is when was it determined that N was or was not > prime? Any time we re-check the calculation we get the same result. > Presumably even causally isolated observers will also get the same result. > If humans get wiped out and cuttlefish take over the world and build > computers, and they check to see if N, is prime is it possible for them to > get a different result? > > My contention is that it is not possible to get a different result, that > N was always prime, or it was always not prime, and it would be prime (or > not prime) even if we lacked the means or inclination to check it. > > > That's fine. But it's a leap to go from the truth value of 17 is prime, > to 17 exists. That's what I mean by mathematicians assuming that > "satisfying a predicate" = "exists". >
I guess it depends on what you mean by existing (I also suspect you knew I'd say that :). I generally consider things that exist are the ones that kick back in some fashion, or as someone said, it's what doesn't go away when you stop believing in it. 17 exists in the sense that it exhibits certain properties that will always be discovered by anyone who performs the relevant calculations, in this universe or any possible universe. And it will continue to do so whether I think it does or not, or whether anyone is around to think it does or not, or whether anyone has ever considered its existence, ever, or not. Whether you think that's good enough to say it exists is, I guess, a matter of taste. Likewise, whether matter or energy exists comes down to what it actually is, which so far nobody knows. My best description of (say) a photon is that it is something that registers a result in certain experiments, e.g. causes a photomultiplier to click or a grain of emulsion to darken. Are those properties worthy of being called existence, any more than being unable to divide 17 by any smaller integers except 1 is? I don't know. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
