  To return to Britain, Hume had a number of successors who accepted the view (which Hume took from Hutcheson) that our fundamental obligation is to work for the greatest happiness of the greatest number. Four are especially significant. William Paley (1743–1805) thought he could demonstrate that morality derived from the will of God and required promoting the happiness of all, that happiness was the sum of pleasures, and that we need to believe that God is the final granter of happiness if we are to sustain motivation to do what we know we ought to do (The Principles of Moral and Political Philosophy, II. 4). Jeremy Bentham (1748–1832) rejected this theological context. His grounds were radically empiricist, that the only ‘real’ entities are publicly observable, and so do not include God (or, for that matter, right or time or relations or qualities). He thought he could provide a scientific calculus of pleasures, where the unit that stays constant is the minimum state of sensibility that can be distinguished from indifference. He thought we could then separate different ‘dimensions’ in which these units vary, such as intensity, duration, certainty, propinquity (how soon the pleasures will come), fecundity (how many other pleasures this pleasure will produce) and purity. Discarding the theological context made moral motivation problematic, for why should we expect (without God) more units of pleasure for ourselves by contributing to the greater pleasure of others? Bentham's solution was to hope that law and social custom could provide individuals with adequate motives through the threat of social sanctions, and that what he called ‘deontology’ (which is personal or private morality) could mobilize hidden or long-range interests that were already present but obscure.