They don’t necessarily exist on different-looking planets. It’s highly unlikely that two planets will look exactly the same, but that’s just because it’s so unlikely for a planet to look exactly like that to begin with. It’s not that one planet looking like that prevents another planet from doing so.
A given hypothesis with many human-level lifeforms is less likely to be filtered out than one with few. For example, imagine that it’s just as likely a priori for there to be one set as two. There’s a 25% chance of life on Earth, a 25% chance of life on Alpha Centari, and a 50% chance of life on both. Then we filter out all the ones without life on Earth, and we’re stuck with a 33% chance of life on Earth and a 67% chance of life on both.
Thanks! What you explain in your second paragraph was what I was missing. The distinction isn’t between hypotheses where there’s one copy of me versus several (those don’t work) but rather between hypotheses where there’s one copy of me versus none, and an early filter falsely predicts lots of “none”s.
They don’t necessarily exist on different-looking planets. It’s highly unlikely that two planets will look exactly the same, but that’s just because it’s so unlikely for a planet to look exactly like that to begin with. It’s not that one planet looking like that prevents another planet from doing so.
A given hypothesis with many human-level lifeforms is less likely to be filtered out than one with few. For example, imagine that it’s just as likely a priori for there to be one set as two. There’s a 25% chance of life on Earth, a 25% chance of life on Alpha Centari, and a 50% chance of life on both. Then we filter out all the ones without life on Earth, and we’re stuck with a 33% chance of life on Earth and a 67% chance of life on both.
Thanks! What you explain in your second paragraph was what I was missing. The distinction isn’t between hypotheses where there’s one copy of me versus several (those don’t work) but rather between hypotheses where there’s one copy of me versus none, and an early filter falsely predicts lots of “none”s.