AbstractOne of the main ideas behind fuzzy logic and its applications is that everything is a matter of degree. We are often accustomed to think that every statement about a physical world is true or false that an object is either a particle or a wave, that a person is either young or not, either well or ill but in reality, we sometimes encounter intermediate situations. In this paper, we show that the existence of such intermediate situations can be theoretically explained by a natural assumption that the real world is cognizable.