Re: Subjective measure? How does that work?

From: Benjamin Udell <>
Date: Sun, 25 Jan 2004 13:18:04 -0500

One might ask Bob, what is the measure of Universes in which a Bob finds M but heeds M' without being suicidal or at least hazardous to his own health? At any rate, Bob could hardly have reached in sound mind & body the cognitive height of many-worlds ideas without heeding M instead of M'. "Why not stick with them's what brung you, Bob?" (Also, it seems to me that Bob might well have to be at least partially heeding familiar M in order to function well enough to try to heed M'.)

Of course, Bob could quip, "Denial is not just a river in Egypt." To some extent, we all stick to one or another interpretation in spite of the interpretation's apparent incoherence, & in spite of apparent contrary evidence. The fact that the incoherence or contrariness may be merely apparent is the temptation (we revise core ideas more reluctantly than others, & rightly so) -- the temptation to go wrong & persist even against a wind of disconfirming information. There is no surefire formula to avoid errors in any of these directions. There's open-mindedness (good) & there's flakiness & wishy-washyness (bad.) There's respect for what has stood the test of time so far (good) & there's dogmatism (bad). (As a practical matter, as regards knowingly to play by a different set of rules than that of the reality which one lives -- it seems to me that psychologically & biologically we are constituted so that we can't do that unless we are insane, & unlikely to be argued back to sanity

- Ben Udell

Hal Finney writes:

>Wei Dai writes:
>> Now suppose that two people, Alice and Bob, somehow agree that a measure M is the objectively correct measure, but Bob insists on using measure M' in making decisions. He says "So what if universe A has a bigger measure than universe B according to M? I just care more about what happens in universe B than universe A, so I'll use M' which assigns a bigger measure to universe B." What can Alice say to Bob to convince him that he is not being rational? I don't see what the answer could be.

>How about if she whacks him on the head? Maybe that would knock some sense into him.

>Seriously, she could confront him with the reality that in the universe branch they are in, measure M works, while M' does not. Reality, whether in the form of a knock on the head or more peaceful interactions, is not subjective.

>Now, true, there would be branches in the multiverse where M' worked while M did not. Believers in objective measure would say that those branches are of low measure and so "don't matter", but as you point out, Bob can argue symmetrically that this branch where he is stuck with Alice and M has worked is also, to him, of low measure.

>But we can solve this conundrum while retaining symmetry. Rationality should demand allegience to the observed measure. It is irrational to cling to a measure which has been rejected repeatedly by observations. If classical definitions of rationality don't have this property, we should fix them. Bob is irrational to hold to M' in a universe whose observations reveal M.

>Now, this will demand that in White Rabbit universes, ones where the quantum or thermodynamic laws just happen to fail due to bad luck, a rational person would have to abandon his (correct!) belief in a lawful universe and come to believe (incorrectly!) in miracles. However this is actually a reasonable requirement, since we are stipulating that such
miracles have been observed.

>Hal Finney
Received on Sun Jan 25 2004 - 13:22:00 PST

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