RE: A calculus of personal identity

From: Stathis Papaioannou <>
Date: Thu, 13 Jul 2006 21:04:11 +1000

Lee Corbin writes:
> > There is an important difference between normative statements and descriptive or empirical statements. Quoting from Wikipedia:> > > > "Descriptive (or constative) statements are falsifiable statements that attempt to describe reality. Normative > > statements, on the other hand, affirm how things should or ought to be, how to value them, which things are good or bad, > > which actions are right or wrong."> > Yes; it's always good to keep that in mind. Catch me if I slip ;-)> > > Suppose some powerful being sets up an experiment whereby organisms who believe they are the same individual day after > > day are selectively culled, while those who believe that they are born anew each morning and die when they fall asleep > > each night, but still make provision for their successors just as we make provision for our children, are left alone or > > rewarded....> > You would then have to grant the day-people that their belief is just as good as ours, > > the difference between us just being an accident of evolution. What's more, to be consistent you would have to grant that > > a duplicate is not a self, on the grounds that the great majority of people do not believe this and our very language is > > designed to deny that such a thing is possible (only the British monarch uses "we" to mean what commoners refer to as "I"). > > Of course, actions speak louder than words. As you point out, people have> believed many seemingly strange things. I'm sure that some medieval> scholastics, or perhaps people in an insane asylum, have consistently> held many positions. What determines sanity, as well as what one's> true beliefs are, is the way that one acts.
This is just the point I was making above: there are (at least) two different kinds of craziness. On the one hand there is the person who jumps off a tall building because he doesn't care if he lives or dies, and on the other hand there is the person who jumps because he thinks he is superman and will be able to fly. The result is the same - both will probably be killed - but one is deluded while the other is not.
> In your example, indeed people could go around saying that they were> not the same person from day to day. But (as you also point out) > evolution might cull certain beliefs. Now what is important is that> someone *acts* as though they are the same from day to day. And in> fact, no matter how people's lips move, we would find that all but> the seriously deranged *act* as though what happened to "them" > tomorrow mattered. > > So I can imagine people *saying* that they are not the same from > day to day, but I cannot imagine successful human organisms acting> as thought they were not.
In the world which we actually live in evolution has, in fact, culled those who don't believe they are the same person from moment to moment, which is why it is such a rare belief. But in the example I gave with the day-people, evolution has had the opposite effect. Intelligent and rational day-people, as described, completely agree on the objective facts of their existence with you, me, and every other rational species. They know that they are made up of substantially the same matter and have mostly the same memories and other mental attributes from day to day, but they report that they believe themselves to be different people from day to day. This would be a false belief regardless of how it evolved if continuity of personal identity were equivalent to physical and/or mental continuity. In our culture, this equivalence is generally taken for granted. But just about every example other than the single branch, birth to death existence with which we are familiar shows that this view is deeply problematic: teleportation, duplication, time travel, fission, parallel universes, alternate evolution, ad hoc psychological changes can all result in "paradoxes" of personal identity if we stubbornly stick to the intuitive, naive theory we have grown up with.
> > Survival and continuity of identity consist solely in the fact that we *believe* we survive from moment to moment.> > Whereas I believe that how we act is what is important, and that our> language should simply reflect how we act. Since people do in fact> try to save their skins over days, in some sense this makes them at> least the same "vested interest".> > In your scenario, language would evolve, although perhaps awkwardly,> to account for people's behavior. For instance, contracts could no> longer be between persons (except ones whose terms expired within> the course of a single day), but instead would specify "vested > interests" or something that meant the same thing as we ordinarily> mean by "person".
Not at all. A system could develop so that people feel responsible for the actions of their predecessors and successors, like a stronger form of the responsibility that we feel for the actions of family members. Some people in our society care more about the welfare of their children than they care about their own welfare, and feel that they will somehow "live on" in their children after their own death, but they certainly don't believe that they are the same person as their children. However, this is beside the point. If truth were a matter of utility, then we could argue that people should believe in heaven and hell if it could be shown that such a belief would have positive social consequences.
> > You're right, of course [in that] The belief that we are the same> > person from moment to moment has a certain utility, otherwise it > > would never have evolved. But do you think there is more to the idea> > than evolutionary expediency?> > Offhand, I can't think of any reason except, as you say, evolutionary> expediency. As you also say, there can be no absolute truth to the > matter. Nonetheless, as I said above, if we want our words to chase> our actual behavior, then there are the usual "persons".> > Notice the great utility of it that even fits the usage I'm suggesting.> Young people strongly discount things that will happen to them when> "they" are much older. But you can see a certain reason to it; in the> sense I use, they may not later be the same person (of course it lies> on a continuum, as you know).> > > Also, if a particular belief or behaviour has evolved, does that> > necessarily makes it true and/or good?> > The belief---as all our beliefs---are either accurate (good maps) or> they are not. We could call our accurate beliefs "true"---isn't that> Tarski's or someone's Correspondence Theory of Truth?.> > For sure, a belief is good, (or perhaps I should simply say better)> if either it advances survival or corresponds to the structure of> the world.
All right. So we can have statements with the following combinations of truth value and moral/social/aesthetic etc. value:
(a) true & good
(b) false & good
(c) true & bad
(d) false & bad
(e) true & neither-good-nor-bad
(f) false & neither-good-nor-bad
(g) neither-true-nor-false & good
(h) neither-true-nor-false & bad
(i) neither-true-nor-false & neither-good-nor-bad
I claim that statements about physical reality, including the biology of an individual, where the matter comprising his body came from, how his present mental state compares to that of similar individuals from the past or coming out of the matter duplicator etc., are of type (a)-(f). Statements of an individual's belief about personal identity (i.e. what beliefs he in fact holds) are also of type (a)-(f). But these beliefs taken on their own, e.g. "I am the same person now as I was 20 years ago", are of type (g)-(i).
Stathis Papaiaonnou
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Received on Thu Jul 13 2006 - 07:05:14 PDT

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