While I definitely don't exclude the possibility of life on other planets, I don't think we have yet any way to calculate the probability of its existence. I c

While I definitely don't exclude the possibility of life on other planets, I don't think we have yet any way to calculate the probability of its existence. I can think of two possibilities to estimate the probability of life outside earth. The first requires knowing, given set of planets excluding earth, how many of them have life on them. We obviously can't use this method yet. Another method is knowing exactly what it takes to create life and then calculating the probability of this process occurring outside earth. We haven't yet managed to synthesise life in a lab (despite headlines which try to claim the contrary). This does not mean we won't be able to create it eventually, but the fact remains that can't yet assess what more is left to make it work. Therefore, you can't assess the probability for it to work anywhere else. Bottom line, I can see no serious formula (Drake's or other) which can give us any estimate at the moment.