Now, how is it that I recognise two names as equivalent? About this, there will not be any dispute. I recognise the meaning of names solely by {389} association. I recognise that such a name is of such a meaning, by association. I recognise that another name is of the same signification, by the same means. That I recognise the meaning of the last, whatever it is, by association, cannot be doubted, because it is by this that the meaning of every word is established. There is, however, another fact; that I recognise the meaning in the second case, as the same with the meaning in the first case. What is the process of this recognition? The word "Man" is the mark or name of a certain cluster of ideas. A certain cluster of ideas I know to be what it is, by having it. Having it, and knowing it, are two names for the same thing. Having it, and having it again, is knowing it, and knowing it again; and that is the recognition of its sameness. It is a single name for the two states of consciousness. This, then, is all that is meant by our belief in the truth of a proposition, the terms of which are convertible, or of equal extent. When of two names, applied to the same thing, one is of less, another of greater extent, the association is more complex; but in that is all the difference. Thus, when I believe the truth of the proposition, "Man is an animal," the meaning of the name "man" is called up by association, and the meaning of the name "animal" is called up by association. Thus far is certain. But there is something further. I recognise, that "animal" is a name of whatever "man" is a name of, and also of more. In having the meaning of the name "man" called up by association, that is, in having the ideas, I recognise that "man" is a name of James, and John, and Homer, and Socrates, and all the individuals of the class. {390} This is pure association. In having the meaning of the name "animal" called up by association, I recognise that it is a name of James, and John, and all the individuals of the same class, as well as of all the individuals of other classes; and this is all that is meant by my Belief in the truth of the proposition. Man is the name of one cluster of ideas; animal is the name of a cluster, including both this and other clusters. The latter cluster is partly the same with, and partly different from, the former. But having two clusters, and knowing them to be two, is not two things, but one and the same thing; knowing them in the case in which I call them same, and knowing them in the case in which I call them different, is still having them, having them such as they are, and nothing besides. In this second case also, of the belief of a proposition, there is, therefore, nothing but ideas, and association.