I'm not claiming life must be common. The strong anthropic theory explains why we can be having this conversation despite the probability of life emerging being arbitrarily low, so there's no reason to assume the probability of life must be high.
But no matter what that probability is, when there are 2 alternative pathways for a step, we should assume the more likely one. I merely claim that
inorganics -> small replicators -> large replicators
But no matter what that probability is, when there are 2 alternative pathways for a step, we should assume the more likely one. I merely claim that
is more likely than