Timothy Leary's credentials
Timothy Leary focused on how the interpersonal process might be used to diagnose disorders and patterns found in human personalities. He proposed that psychedelic substances, used at proper dosages, in a stable set and setting could, under the guidance of psychologists, alter behavior in beneficial ways not easily attainable through regular therapy. Subsequently he had developed a following of admirers for the philosophy turn on, tune in, drop out. This was commonly understood to suggest that taking psychedelic drugs (in particular LSD) was valuable to average people.
Jerome Lettvin's credentials
Trained by neurologist Denny Brown, Jerome Lettvin was a psychiatrist, neurologist, neurosurgeon, and neuroscientist with deep clinical experience and was a passionate advocate of individual rights. Having been the head of only 7 doctors controlling the 7,000 patients in Manteno State Hospital, he had direct experience diagnosing a large number of unusual neurological conditions along with their treatments, useful drugs, and their effectiveness.