X-Message-Number: 26683 Date: Sun, 24 Jul 2005 09:47:23 -0400 From: Thomas Donaldson <> Subject: for Mike Perry once more For Mike Perry once more: No, I am not describing equivalence as compared to identity. The thing to remember about mathematics is that it consists of abstract theories which we apply in different contexts. We apply such theories by considering objects, relations, and changes in a real system by using one or another abstract theory. This applies to the notion of "identity" as well as it applies to other theoretical notions such as "linear" or "addition" or "multiplication". And thinking this way turns out to be VERY useful. To move to the notion of identity in human beings, notions of identity in which I differ fundamentally from myself 1 minutes ago can be easily devised. After all, I breathe, fart, and touch things constantly, and thus bring in new molecules and send out other molecules constantly. So I am never identical to myself. In math I raised the notion of two functions being identical even when they differed at a countable number of points. How could that make them identical? Because their integrals, convolutions, Laplace transforms, Fourier transforms, and any other operation which integrates the function when combined with others in any way will come out "the same" --- again, if the result is a function (for instance) it will be the identical function (by this definition). How would the above notion of identity for human beings be useful? If we really want to study inflow and outflow of energy and materials from our bodies, we need ways to distinguish people who normally would be said to be the same. Abstract theories should never ever ever be confused with real events. That makes them MORE useful rather than less. In one sense I am the "same" person I was when I was 10 years old, in another sense of identity I am not the same. WE choose the sense of identity we wish to use; the only obligation on us when we do so is that we do not get confused and apply two DIFFERENT senses of identity in talking about the same subjects. I carry the same genes as I did when I was 10; I carry a subset of the memories I had when I was 10: I remembered my name as Thomas Donaldson, then and now, recognized my sisters and parents, and many other features remain the same. Yes, others have changed, but in the sense of identity I am using right now I am the "same" person. No law prevents me also from using a different sense of identity which says that I am a different person than the person I was when I was 10. My knowledge and skills in various fields differs from those I had when I was 10; my body has changed its shape and form since I was 10. I have diseases and disabilities I did not have when I was 10. The one point which I should not fail is that I should distinguish these two senses of identity. There is no such thing as identity separate from a choice, implicit or explicit, of the different and same features which define it. And of course to be reasonable we must try to make such a choice explicit --- otherwise we will find ourselves tied up in knots by the different senses of identity we have used. Best wishes and long long life for all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26683