The article traces the origination of the psychological concept of the ‘herd instinct’, popularized by British surgeon Wilfred Trotter, locating this in a distinctive moment of dialogue between the natural and human sciences. It challenges the incorrect association of Trotter’s model with the crowd theory of Gustave Le Bon and negative commentaries on mass culture. In contrast, it shows that Trotter’s model rests on imitation and suggestion not as the sign of a derogated culture but as the ground of associated (...) life, with altruism as its highest expression. His argument that individuals possessed an inherent capacity for association and a disposition to act in the interests of the social group was designed to challenge the hierarchical models of Social Darwinism. Instead, he highlighted the evolutionary importance of variability and innovation and proposed a horizontal model of cooperation as the basis of adaptation. Trotter’s narrative of human potential pre-dated and informed Freud’s own collective psychology, as well as providing an influential challenge to his theory of repression. The widespread take-up of Trotter’s model of the herd instinct in the context of futures thinking, forming the basis of an egalitarian approach to governance that proposed human fulfilment and social progress as complementary aims, supports the article’s argument that psychological approaches to collectivity were well established prior to the First World War rather than formed in response to it, and that these were embedded within social thinking across the political spectrum, rather than derived for instrumentally conservative purposes. (shrink)