An approach to the theory of meaning that follows an insight of F. P. Ramsey, who points out (in ‘Facts and Propositions’) that we might say that a chicken believes that a kind of caterpillar is poisonous if the chicken’s actions ‘were such as to be useful if, and only if the caterpillars were actually poisonous’. The approach cements together the likelihood of satisfying a desire with the truth of the belief on which the agent acts. It is thus a way of developing a kind of pragmatism.