In deontic logic, the principle that if an agent ought to bring about , then must be able to bring about , summarized by the slogan that ‘ought implies can’. Formally, in deductive systems with modalities and interpreted as ‘it is obligatory that…’ and ‘it is possible that…’, respectively, this intuition is captured by the axiom . Named after the philosopher Immanuel Kant (1724–1804), in whose moral philosophy of duties and obligations an informal version of the principle is endorsed.