We have a strong subjective sense of personal experience which is optimized for passing on genes, and which thus coincides with the Born probabilities. In addition, it seems biased toward “only one of me” thinking (evidence: most people’s intuitive rejection of MWI as absurd even before hearing any of the physics, and most people’s intuitive sense that if duplicated, ‘they’ will be the original and ‘someone else’ will be the copy). The plausible ev-psych explanation for this, ISTM, is that you won’t ever encounter another version of your actual self, and that it’s very bad to be tricked into really loving your neighbor as yourself. Thus the rigid sense of continuity of personal identity.
Thus, when complications like quantum suicide or splitting or merging of minds are introduced, the basic intuitions become extremely muddled. In particular, Nick Bostrom’s solution prompts the objection of absurdity, even though it is made up of ingredients that seem reasonable (to rationalist materialists, anyhow) taken separately. That makes me suspicious that Bostrom might in fact be right, and that our objections stem more from the ev-psych than anything else.
The following thought experiment pumps my intuition: what concept of subjective probability might Ebborian-like creatures evolve? Of course, they’d split more frequently when resources were plentiful. Imagine that a quantum random event X would double an Ebborian’s resources if it happened, and that X happened in half the branches of the wavefunction. If it’s assumed that the Ebborian would split if and only if X happened, what subjective probability would ve evolve to assign to X? Well, since what really counts for the evolutionary process is the total ‘population of descendants’ averaged across all branches, ve should in fact weight more heavily the futures in which ve splits: ve should evolve to assign X probability 2⁄3, even though the splitting happens after observing X. And there’s really no inconsistency with that: the single copy in half the branches feels a bit unlucky while the two copies in the other branches rejoice that the odds were in their favor. Repeat this a great many times, and most of the descendants will feel pretty well calibrated in their probabilities.
So I think that our sense of subjective probability has to be an evolved aid to decision-making, rather than an inherent aspect of conscious experience; and I have to go with Nick Bostrom’s probabilities, as strange as they sound. (Nods to Tyrrell and Wei Dai, whose comments greatly helped my thought process.)
ETA: I just realized an ingredient of “what it would feel like”: Ebborians would evolve to give the same probabilities we would for events that don’t affect their splitting times, but all events that would make them richer or poorer would have subjective probability skewed in this fashion. Basically, Ebborians evolve so that each one just feels that being a consistently lucky frood is the natural state of things, and without that necessarily giving them the ego it would give us.
Suppose that the Ebborians gamble. What odds would it give for event X?
Suppose ve gives odds of 2:1 (probability of 2⁄3). A bookie takes the bet, and in half of the branches, collects 2 (from the two “descendants”), and in half of the branches, pays out 1, for an average profit of 0.5.
I think your argument leads to the Ebborians being vulnerable to Dutch books.
Er, your math is the wrong way around, but your point at first seems right: the Ebborian sees 2⁄3 odds, so ve is willing to pay the bookie 2 if X doesn’t happen, and get paid 1 (split between copies, as in correlated decision theory) if X does happen.
However, if instead the Ebborian insists on paying 2 for X not happening, but on each copy receiving 1 if X happens, the Dutch book goes away. Are there any inconsistencies that could arise from this sort of policy? Perhaps the (thus developed) correlated decision theory only works for the human form of subjective probability? Or more probably, I’m missing something.
We have a strong subjective sense of personal experience which is optimized for passing on genes, and which thus coincides with the Born probabilities. In addition, it seems biased toward “only one of me” thinking (evidence: most people’s intuitive rejection of MWI as absurd even before hearing any of the physics, and most people’s intuitive sense that if duplicated, ‘they’ will be the original and ‘someone else’ will be the copy). The plausible ev-psych explanation for this, ISTM, is that you won’t ever encounter another version of your actual self, and that it’s very bad to be tricked into really loving your neighbor as yourself. Thus the rigid sense of continuity of personal identity.
Thus, when complications like quantum suicide or splitting or merging of minds are introduced, the basic intuitions become extremely muddled. In particular, Nick Bostrom’s solution prompts the objection of absurdity, even though it is made up of ingredients that seem reasonable (to rationalist materialists, anyhow) taken separately. That makes me suspicious that Bostrom might in fact be right, and that our objections stem more from the ev-psych than anything else.
The following thought experiment pumps my intuition: what concept of subjective probability might Ebborian-like creatures evolve? Of course, they’d split more frequently when resources were plentiful. Imagine that a quantum random event X would double an Ebborian’s resources if it happened, and that X happened in half the branches of the wavefunction. If it’s assumed that the Ebborian would split if and only if X happened, what subjective probability would ve evolve to assign to X? Well, since what really counts for the evolutionary process is the total ‘population of descendants’ averaged across all branches, ve should in fact weight more heavily the futures in which ve splits: ve should evolve to assign X probability 2⁄3, even though the splitting happens after observing X. And there’s really no inconsistency with that: the single copy in half the branches feels a bit unlucky while the two copies in the other branches rejoice that the odds were in their favor. Repeat this a great many times, and most of the descendants will feel pretty well calibrated in their probabilities.
So I think that our sense of subjective probability has to be an evolved aid to decision-making, rather than an inherent aspect of conscious experience; and I have to go with Nick Bostrom’s probabilities, as strange as they sound. (Nods to Tyrrell and Wei Dai, whose comments greatly helped my thought process.)
ETA: I just realized an ingredient of “what it would feel like”: Ebborians would evolve to give the same probabilities we would for events that don’t affect their splitting times, but all events that would make them richer or poorer would have subjective probability skewed in this fashion. Basically, Ebborians evolve so that each one just feels that being a consistently lucky frood is the natural state of things, and without that necessarily giving them the ego it would give us.
Suppose that the Ebborians gamble. What odds would it give for event X?
Suppose ve gives odds of 2:1 (probability of 2⁄3). A bookie takes the bet, and in half of the branches, collects 2 (from the two “descendants”), and in half of the branches, pays out 1, for an average profit of 0.5.
I think your argument leads to the Ebborians being vulnerable to Dutch books.
Er, your math is the wrong way around, but your point at first seems right: the Ebborian sees 2⁄3 odds, so ve is willing to pay the bookie 2 if X doesn’t happen, and get paid 1 (split between copies, as in correlated decision theory) if X does happen.
However, if instead the Ebborian insists on paying 2 for X not happening, but on each copy receiving 1 if X happens, the Dutch book goes away. Are there any inconsistencies that could arise from this sort of policy? Perhaps the (thus developed) correlated decision theory only works for the human form of subjective probability? Or more probably, I’m missing something.
From the bookie’s perspective, the “each copy” deal corresponds to 1:1 odds, right?