NEW SERIES. No. 35.] [JULY, 1900. MIND A QUARTERLY REVIEW OF PSYCHOLOGY AND PHILOSOPHY. I. NECESSITY. BY DR. G. E. MOORE. MY primary object in this paper is to determine the meaning of necessity. I do not wish to discover what things are necessary ; but what that predicate is which attaches to them when they are so. Nor, on the other hand, do I wish to arrive at a correct verbal definition of necessity. That the word is commonly used to signify a great number of different predicates, which do actually attach to things, appears to me quite plain. But, this being so, we shall be using the word correctly, whenever we apply it to any one of these ; and a correct definition of necessity will be attained, if we enumerate all those different predicates which the word is commonly used to signify : for the only test that a word is correctly defined is common usage. The problem which I wish to solve is different from either of these. It is a problem which resembles them in its universal application. There is a solution of it not only for necessity but for every- thing that we can think of ; and in many cases the discovery of this solution appears to me to be of fundamental import- ance for philosophy. The nature of this problem may perhaps be exhibited as follows : When a man says ' A is necessary ' or ' red ' or ' round ' or ' loud ' or, whatever it may be, he may be wrong in three ways. (1) He may be using the word ' necessary ' in a sense in which it is not commonly used. For instance the thought which he intends to convey may be that ' A is red ' ; and then, whether A is red or not, he is committing a verbal error in saying that ' A is necessary '. 19
