A much more plausible filter, along the same lines, is earth not ever going outside a certain range of temperatures, over four billions years or so, as Sun shone brighter.
There could be many filters along the same lines, such as never happening evolution of a very successful but simple organism that eats everything complex, prompting a restart.
Given our own existence, we can perhaps rule out theories which give very low probability of emergence of life in the whole universe, but the probability of emergence of life on a given habitable planet may still be incredibly low (if some molecules have to randomly combine in a certain specific way).
A much more plausible filter, along the same lines, is earth not ever going outside a certain range of temperatures, over four billions years or so, as Sun shone brighter.
There could be many filters along the same lines, such as never happening evolution of a very successful but simple organism that eats everything complex, prompting a restart.
Given our own existence, we can perhaps rule out theories which give very low probability of emergence of life in the whole universe, but the probability of emergence of life on a given habitable planet may still be incredibly low (if some molecules have to randomly combine in a certain specific way).