I will begin with C, the difference between a belief and a statement. By a “statement” I mean a form of words, uttered or written, with a view to being heard or read by some other person or persons, and not a question, interjection, or command, but such as we should call an assertion. As to the question what forms of words are assertions, that is one for the grammarian and differs from language to language. But perhaps we can say rather more than that. The distinction, however, between an assertion and an imperative is not sharp. In England, notices say “Visitors are requested not to walk on the grass”. In America, they say “Keep off! This means you.” Effectively, the two have the same meaning: yet the English notice consists only of a statement, while the American notice consists of an imperative followed by a statement which must be false if read by more than one person. In so far as statements are intended to influence the conduct of others, they partake of the nature of imperatives or requests. Their characteristic, however, is that they endeavour to effect their aim by producing a _belief_ which may or may not exist in the mind of the speaker. Often, however, they _express_ a belief, without stopping to consider the effect upon others. Thus a statement may be defined as a form of words which either expresses a belief or is intended to create one. Our next step, therefore, must be the definition of “belief”. “Belief” is a word which will be quite differently defined if we take an analytic point of view from the way in which we shall define it if we regard the matter causally. From the point of view of science, the causal point of view is the more important. Beliefs influence action in certain ways; what influences action in these ways may be called a belief, even if, analytically, it does not much resemble what would ordinarily be so called. We may therefore widen our previous definition of belief. Consider a man who goes to the house where his friend used to live, and, finding he has moved, says, “I _thought_ he still lived here”, whereas he acted merely from habit without thought. If we are going to use words causally, we ought to say that this man had a “belief” and therefore a “belief” will be merely a characteristic of a string of actions. We shall have to say: A man “believes” a certain proposition _p_ if, whenever he is aiming at any result to which _p_ is relevant, he acts in a manner calculated to achieve the result if _p_ is true, but not otherwise. Sometimes this gives definite results, sometimes not. When you call a telephone number, it is clear that you believe that to be the number of the subscriber you want. But whether you believe in the conservation of energy or a future life may be harder to decide. You may hold a belief in some contexts and not in others; for we do not think in accordance with the so-called “Laws of Thought”. “Belief” like all the other categories of traditional