If you're sticking to statistics, the right answer is we don't know enough. The general rule of thumb I've seen is that you want to see n * p >= ~20 to be able to accurately assess the probability.
For the difficulty of evolution of life, we have a total N of 1-5 of life-could-have-evolved, depending on how optimistic or pessimistic you want to be about life's chances (could life have evolved on Venus? Mars? Titan? Europa? any other moons I'm forgetting about).
At this point, the statistics says more about your priors than they do about actual data, since there's not enough data to actually do any statistics on.
For the difficulty of evolution of life, we have a total N of 1-5 of life-could-have-evolved, depending on how optimistic or pessimistic you want to be about life's chances (could life have evolved on Venus? Mars? Titan? Europa? any other moons I'm forgetting about).
At this point, the statistics says more about your priors than they do about actual data, since there's not enough data to actually do any statistics on.