the key word here is "probably". rationak people do not believe their assumptions are absolute. they make educated guesses on the information available and are ready to update their world view based on new information. right now we are not in a position to judge how common life is in the universe. it's just very probable based on the size and sheer number of planets that exist. if we discover another life form or hints of life just in this solar system the probability that life exists outside of our system is far beyond 99.99% if we travel the universe for billions of years and don't find any evidence of alien life then we would conclude that life on earth is an anomaly but we are not at that stage yet.
Republican