American psychiatrist, founder of the interpersonal school of psychoanalysis, and the dominant figure in the mid-century American effort to ground psychiatry in social rather than strictly intrapsychic terms. Where Freud located the raw material of psychic life in the biological drives, Sullivan located it in the field of relations between persons: personality, on his account, is the relatively enduring pattern of recurrent interpersonal situations that characterize a human life, and the proper unit of psychiatric study is not the isolated individual but the two-or-more-person field in which disturbances actually take form.
His clinical reputation rested on unusual therapeutic success with schizophrenic patients at Sheppard Pratt in the 1920s — work that undercut the Kraepelinian consensus that schizophrenia was a purely organic deterioration. From this Sullivan developed an account of anxiety as the primary disorganizing force in human life — anxiety transmitted interpersonally, first from mother to infant, and managed thereafter through the "self-system," the set of security operations by which a person keeps anxiety out of awareness at the cost of restricting the self. His late lectures, posthumously published as The Interpersonal Theory of Psychiatry (1953), are the canonical statement.
Sullivan's influence ran in several directions. He was a co-founder, with Clara Thompson, Erich Fromm, and Karen Horney, of the William Alanson White Institute, the American center of cultural and interpersonal psychoanalysis. His work shaped Erikson's developmental scheme and Fromm's social psychology. And — relevantly for this graph — Walker Percy regarded Sullivan as a major influence, taking from him the conviction that the self is constituted in the intersubjective field and that language is the medium in which that constitution happens. Percy's own "semiotic" anthropology develops this Sullivanian starting point in a direction Sullivan himself did not take.