  The first reason is epistemic or evidential. Warrant or evidence for saying, at least in the third person case, that an animal or person is in a certain mental state, for example, possesses a certain belief, is grounded in behavior, understood as observable behavior. Moreover, the conceptual space or step between the claim that behavior warrants the attribution of belief and the claim that believing consists in behavior itself is a short and in some ways appealing step. If we look, for example, at how people are taught to use mental concepts and terms—terms like “believe”, “desire”, and so on—conditions of use appear inseparably connected with behavioral tendencies in certain circumstances.  If mental state attribution bears a special connection with behavior, it is tempting to say that mentality just consists in behavioral tendencies.