There is no evidence which strongly contradicts the hypothesis that life arose on Earth due to such extraordinarily improbable events that it is extremely unlikely it has arisen or will ever arise elsewhere within the observable universe. Moreover, a few bits of evidence and lines of reasoning support this hypothesis, though none in a conclusive or compelling way. The ways in which molecular biology suggests combinatoric improbability, the Fermi(-Hart) paradox, “rare Earth” lines of argument and the failure to date of SETI are among them. Moreover, some of the most common counterarguments to these inferences are flawed in fundamental ways. However unappealing it may be (to most, but not all), we should take the hypothesis quite seriously at our current state of knowledge. It is arguably as good as any other available scenario on a purely empirical basis.
Talk Host: Joshua Winn