Sheaffer naît le à Chicago (Illinois, USA).
Il développe une position rationaliste.
Auteur de :
- Resentment Against Achievement, Prometheus Books, Buffalo, NY, 1988, Cloth, ISBN 0-87975-447-8.
- The Making of the Messiah, Prometheus Books, Buffalo, NY, 1991, Cloth, ISBN 0-87975-691-8
- (1997). "The truth is, they never were `saucers.'" Skeptical Inquirer, 21, 5, 22.
- UFO Sightings - The Evidence, Prometheus Books, Amherst, NY, cloth, 1998, ISBN 1-57392-213-7