It is a well-known fact in the history of philosophy that _necessary_ truths in general, but especially those of which it is said that the opposite is inconceivable, have been commonly supposed to be _analytic,_ in the sense that the proposition denying them was self-contradictory. It was in this way, commonly supposed, before Kant, that many truths could be proved by the law of contradiction alone. This is, therefore, a mistake which it is plainly easy for the best philosophers to make. Even since Kant many have continued to assert it; but I am aware that among those Idealists, who most properly deserve the name, it has become more fashionable to assert that truths are _both_ analytic and synthetic. Now with many of their reasons for asserting this I am not concerned: it is possible that in some connexions the assertion may bear a useful and true sense. But if we understand 'analytic' in the sense just defined, namely, what is proved by the law of contradiction _alone_, it is plain that, if 'synthetic' means what is _not_ proved by this alone, no truth can be both analytic and synthetic. Now it seems to me that those who do maintain truths to be both, do nevertheless maintain that they are so in this as well as in other senses. It is, indeed, extremely unlikely that so essential a part of the historical meaning of 'analytic' and 'synthetic' should have been entirely discarded, especially since we find no express recognition that it is discarded. In that case it is fair to suppose that modern Idealists have been influenced by the view that certain truths can be proved by the law of contradiction alone. I admit they also expressly declare that they can _not:_ but this is by no means sufficient to prove that they do not also think they are; since it is very easy to hold two mutually contradictory opinions. What I suggest then is that Idealists hold the particular doctrine in question, concerning the relation of subject and object in experience, because they think it is an analytic truth in this restricted sense that it is proved by the law of contradiction alone.
I am suggesting that the Idealist maintains that object and subject are necessarily connected, mainly because he fails to see that they are _distinct_, that they are _two,_ at all. When he thinks of 'yellow' and when he thinks of the 'sensation of yellow,' he fails to see that there is anything whatever in the latter which is not in the former. This being so, to deny that yellow can ever _be_ apart from the sensation of yellow is merely to deny that yellow can ever be other than it is; since yellow and the sensation of yellow are absolutely identical. To assert that yellow is necessarily an object of experience is to assert that yellow is necessarily yellow--a purely identical proposition, and therefore proved by the law of contradiction alone. Of course, the proposition also implies that experience is, after all, something distinct from yellow--else there would be no reason for insisting that yellow is a sensation: and that the argument thus both affirms and denies that yellow and sensation of yellow are distinct, is what sufficiently refutes it. But this contradiction can easily be overlooked, because though we are convinced, in other connexions, that 'experience' does mean something and something most important, yet we are never distinctly aware _what_ it means, and thus in every particular case we do not notice its presence. The facts present themselves as a kind of antinomy: