To add to Abigail’s point:
Is there significant evidence that the critically low term in the Drake Equation isn’t f_i (i.e. P(intelligence|life))? If natural selection on earth hadn’t happened to produce an intelligent species, I would assign a rather low probability of any locally evolved life surviving the local sun going nova.
I don’t see any reasonable way of even assigning a lower bound to f_i.
To add to Abigail’s point: Is there significant evidence that the critically low term in the Drake Equation isn’t f_i (i.e. P(intelligence|life))? If natural selection on earth hadn’t happened to produce an intelligent species, I would assign a rather low probability of any locally evolved life surviving the local sun going nova. I don’t see any reasonable way of even assigning a lower bound to f_i.