III—Optimism in the Search for Extraterrestrial Life? A Philosophical Perspective

Abstract The large number of planets in our galaxy is often appealed to as the basis for optimism that life exists beyond earth in sufficiently large quantities that we might reasonably hope to detect or otherwise encounter it. In an article published over thirty years ago, Roy Mash argued against this inference on broadly philosophical grounds. It is argued that, despite scientific advances in recent decades, the spirit of Mash’s case stands and optimism remains under-supported.