facts; or more exactly, he wished to establish the existence of certain dubitable facts on a rational basis. The modern investigations of which I speak seek to analyse facts whose existence is not disputed. Analysis may of course lead to scepticism, but scepticism has too seldom led to analysis, and the distinction between the two interests in themselves is of the widest.
In no case is it wider than in the particular problem which I wish now to consider, the elementary question whether an idea, which is one existence, can know an object, which is another; or, as I shall put it, what we mean by true opinion and false, by knowledge and error. The difficulty that waits to thwart us here is among the deepest difficulties in thought. I am not unaware of the literature existing on this subject, from the Greeks through Fichte, Hegel and their followers, to certain writers of the present day, though from some points of view it seems to me surprisingly slight; I shall not, however, be obliged to discuss it here. An exception may be made for the presentation of the difficulty contained in the work of Professor Josiah Royce, The Religious Aspect of Philosophy. The method and matter of Professor Royce's conclusion I am unable to accept, but his statement of the problem is of much value. I must set it down here, however, in my own terms.
We believe ourselves to know existences external to our minds. We believe ourselves to know, for example, the minds of others. How do we know them? By having correct ideas of them. But an idea is merely a particular appearance in the mind; it presents itself to us, but it can tell us of nothing beyond itself. If there are external existences, my ideas can at best resemble them. But resemblance is not knowledge. The south tower of Cologne Cathedral resembles the north tower, but does not therefore know it. In order to have true knowledge, not only must my ideas resemble certain external things, but I must mean them to resemble those external things. A thought of mine cannot be accused of error about an outer fact, if I did not mean it to refer to that fact. My ideas are not responsible for their chance resemblances. But
