I think it's fairly obvious that p(biosphere | habitable zone) > p(biosphere | !habitable zone).
Could you please explain that formula in layman's language?
I never got any higher in math than first-year algebra.
The probability of a biosphere given that a planet is in the habitable zone is greater than the probability of a biosphere given that a planet is not in the habitable zone.
This does not say a biosphere is likely, just that it's more
likely by a nonzero amount.