Absence of Evidence Is Not Evidence of Absence

Carl Sagan? Martin Rees? William Wright? William Housman? W. J. Sollas? Dugald Bell? Anonymous? Dear Quote Investigator: The existence or non-existence of intelligent extraterrestrial life is a highly contentious subject. Some thinkers who are open to the possibility of interstellar aliens also believe that the current evidence is inadequate; hence, they advocate using radio telescope …