Of course from a physical point of view, (e.g. from the point of view of Many Worlds QM or the lower Tegmark levels) there are lots of human instances around in the multiverse, all thinking that their particular bit of the multiverse is “real”. Clearly, they cannot all be right. This is somewhat worrying; naive ideas about our little part of the universe being real, and the rest imaginary, are probably a “confusion”, so we end up (as Wei D says) having to turn our old-fashioned epistemological intuitions into ethical principles; principles such as “I only care about the world that I am actually in”, or we have to leave ourselves open to turning into madmen who do bizarre things to themselves for expected reward in other possible universes.
And formalizing “the universe I am actually in” may not be easy; unless we are omniscient, we cannot have enough data to pin down where exactly in the multiverse we are.
Of course from a physical point of view, (e.g. from the point of view of Many Worlds QM or the lower Tegmark levels) there are lots of human instances around in the multiverse, all thinking that their particular bit of the multiverse is “real”. Clearly, they cannot all be right. This is somewhat worrying; naive ideas about our little part of the universe being real, and the rest imaginary, are probably a “confusion”, so we end up (as Wei D says) having to turn our old-fashioned epistemological intuitions into ethical principles; principles such as “I only care about the world that I am actually in”, or we have to leave ourselves open to turning into madmen who do bizarre things to themselves for expected reward in other possible universes.
And formalizing “the universe I am actually in” may not be easy; unless we are omniscient, we cannot have enough data to pin down where exactly in the multiverse we are.