In either case, asking “but what’s the probability, really?” isn’t helpful.
Strongly agree. My paper here: http://arxiv.org/abs/1110.6437 takes the problem apart and considers the different components (utilities, probabilities, altruism towards other copies) that go into a decision, and shows you can reach the correct decision without worrying about the probabilities at all.
You’re wondering whether or not to donate to reduce existential risks. You won’t donate if you’re almost certain the world will end soon either way. You wake up as the 100 billionth person. Do you use this information to update on the probability that there will only be on the order of 100 billion people, and refrain from donating?
Strongly agree. My paper here: http://arxiv.org/abs/1110.6437 takes the problem apart and considers the different components (utilities, probabilities, altruism towards other copies) that go into a decision, and shows you can reach the correct decision without worrying about the probabilities at all.
You’re wondering whether or not to donate to reduce existential risks. You won’t donate if you’re almost certain the world will end soon either way. You wake up as the 100 billionth person. Do you use this information to update on the probability that there will only be on the order of 100 billion people, and refrain from donating?