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