Abstract

Intelligence, genius and mental ability were a cluster of traits that received much attention in eugenics discourse. Intelligence was regarded as one of the good qualities superior men possessed, in turn beneficial for society as a whole. On the other hand, the socially problematic or unproductive were identified as being of inferior mental quality: “feeble-minded”. By and large, eugenicists thought that (1) intelligence was a unitary psychological trait that could be measured, being quantified as an intelligence quotient (IQ); (2) intelligence was paired with educational achievement, reputation, and economic success; (3) a certain degree of intelligence was necessary to act morally and to foresee the consequences of one’s actions. Despite the prominent role of intelligence in the history of eugenics, there is considerable lack of clarity in what this general mental ability was considered to be.