C. E. M. Hansel

British psychologist and skeptic who wrote ESP: A Scientific Evaluation (1966) — arguing that all parapsychological experiments were flawed by inadequate controls or outright fraud — becoming the most influential scientific critic of parapsychology in the 20th century.

Articulated the skeptical methodological standard: if ESP exists, it must be demonstrable under conditions where all conventional explanations are impossible — and systematically argued that Rhine's experiments and subsequent replications always left some loophole for conventional explanation.