Putative problems and pure progress in neuropsychological Single-Case studies

We consider the logic of basing theories of normal and pathological cognitive functioning upon the selective deficits revealed by single-case studies. Objections to this strategy, concerned with the rarity of pertinent cases, the role of methodological artifacts, and the existence of normal variation in brain functions are refuted. We conclude that, in neuropsychology, a group has no significance over and above the individual members it contains.