"If – as I hope is the case – we are the only intelligent species that has ever evolved in our galaxy, and perhaps in the entire observable universe, it does no

"If – as I hope is the case – we are the only intelligent species that has ever evolved in our galaxy, and perhaps in the entire observable universe, it does not follow that our survival is not in danger. Nothing in the above reasoning precludes the Great Filter from being located both behind us and ahead of us. It might both be extremely improbable that intelligent life should arise on any given planet, and very improbable that intelligent life, once evolved, should succeed in becoming advanced enough to colonize space. "But we would have some grounds for hope that all or most of the Great Filter is in our past if Mars is indeed found to be barren." It would not give grounds for that hope; it would merely, and at most, not give grounds for suspecting that the hope is in vain. Bostrom cannot quantify how likely his hope is, and what he is praying for here is to maintain that ignorance - to not learn anything that might help quantify the probability in a direction inconsistent with his hope. This strikes me as contrary to the ideals of philosophy.