Picking up on John Forrester’s (1949–2015) disclosure that he felt ‘haunted’ by the suspicion that Thomas Kuhn’s (1922–96) interests had become his own, this essay complexifies our understanding of both of their legacies by presenting two sites for that haunting. The first is located by engaging Forrester’s argument that the connection between Kuhn and psychoanalysis was direct. (This was the supposed source of his historiographical method: ‘climbing into other people’s heads’.) However, recent archival discoveries suggest that that is incorrect. Instead, (...) Kuhn’s influence in this regard was Jean Piaget (1896–1980). And it is Piaget’s thinking that was influenced directly by psychoanalysis. Psychoanalysis then haunts Kuhn’s thinking through Piaget, and thus Piaget haunts Forrester through Kuhn. To better understand this second site of the haunting—which is ultimately the more important one, given the intent of this special issue—Piaget’s early psychoanalytic ideas are uncovered through their interaction with his early biology and subsequent turn to philosophy. But several layers of conflicting contemporary misunderstandings are first excavated. The method of hauntology is also developed, taking advantage of its origins as a critical response to the psychoanalytic discourse. As a result of adopting this approach, a larger than usual number of primary sources have been unearthed and presented as evidence (including new translations from French originals). Where those influences have continued to have an impact, but their sources forgotten, they have thus been returned. They can then all be considered together in deriving new perspectives of Forrester’s cases/Kuhn’s exemplars/Piaget’s stages. (shrink)