Is intelligence hard to evolve? Well, we’re intelligent, so it must be easy… except that only an intelligent species would be able to ask that question, so we run straight into the problem of anthropics. Any being that asked that question would have to be intelligent, so this can’t tell us anything about its difficulty
I think the line of reasoning is valid, it’s just that there’s a lot of confusion about probabilities and events to which the probabilities apply. Of course the probability of life arising—once in the whole universe—is high—very close to 1, given that we are very sure we in fact exist.
What we want to know is the distance to the nearest other-origin intelligent life, and that’s where anthropics shouldn’t be able to help us at all. Even if you subscribe to the notion that the probability of our existence is in some way proportional to the number of intelligent beings, that does not in any way whatsoever privilege a smaller universe with the same number of intelligent beings over a larger universe (with those beings spread further apart as measured in the sizes of the intelligent being).
It’d also seem that one could take a good look at the known laws of physics, think really hard thoughts that we can’t think yet, and compute a good approximation to the density of intelligent beings in the universe. Which renders alternatives—same laws of physics, different density of beings—logically impossible.
Of course the probability of life arising—once in the whole universe—is high—very close to 1, given that we are very sure we in fact exist.
Don’t think this works. For all we know, the vast majority of possible universes are entirely dead, and only our tiny backwater of configuration space happened upon the right low-probability event. The probability of life existing given that we’re in a configuration with life in it is of course 1, but we can’t use that to derive a high probability for abiogenesis without independent data points, which we don’t have.
(This is unlikely to actually be the case, of course—unicelluluar life appeared so early in our planet’s history that we can’t pinpoint it with stratigraphic methods, which is unlikely if abiogenesis were the hard part. But we’re talking unlikely, not impossible or nearly impossible.)
Regarding anthropics, specifically this:
I think the line of reasoning is valid, it’s just that there’s a lot of confusion about probabilities and events to which the probabilities apply. Of course the probability of life arising—once in the whole universe—is high—very close to 1, given that we are very sure we in fact exist.
What we want to know is the distance to the nearest other-origin intelligent life, and that’s where anthropics shouldn’t be able to help us at all. Even if you subscribe to the notion that the probability of our existence is in some way proportional to the number of intelligent beings, that does not in any way whatsoever privilege a smaller universe with the same number of intelligent beings over a larger universe (with those beings spread further apart as measured in the sizes of the intelligent being).
It’d also seem that one could take a good look at the known laws of physics, think really hard thoughts that we can’t think yet, and compute a good approximation to the density of intelligent beings in the universe. Which renders alternatives—same laws of physics, different density of beings—logically impossible.
Don’t think this works. For all we know, the vast majority of possible universes are entirely dead, and only our tiny backwater of configuration space happened upon the right low-probability event. The probability of life existing given that we’re in a configuration with life in it is of course 1, but we can’t use that to derive a high probability for abiogenesis without independent data points, which we don’t have.
(This is unlikely to actually be the case, of course—unicelluluar life appeared so early in our planet’s history that we can’t pinpoint it with stratigraphic methods, which is unlikely if abiogenesis were the hard part. But we’re talking unlikely, not impossible or nearly impossible.)