has the property x also has the property that it is experienced. And this being so, it will be convenient if, for the future, I may be allowed to use the term ‘esse’ to denote x alone. I do not wish thereby to beg the question whether what we commonly mean by the word ‘real’ does or does not include percipi as well as x. I am quite content that my definition of ‘esse’ to denote x, should be regarded merely as an arbitrary verbal definition. Whether it is so or not, the only question of interest is whether from x percipi can be inferred, and I should prefer to be able to express this in the form: can percipi be inferred from esse? Only let it be understood that when I say esse, that term will not for the future include percipi: it denotes only that x, which Idealists, perhaps rightly, include along with percipi under their term esse. That there is such an x they must admit on pain of making the proposition an absolute tautology; and that from this x percipi can be inferred they must admit, on pain of making it a perfectly barren analytic proposition. Whether x alone should or should not be called esse is not worth a dispute: what is worth dispute is whether percipi is necessarily connected with x.
We have therefore discovered the ambiguity of the copula in esse is percipi, so far as to see that this principle asserts two distinct terms to be so related, that whatever has the one, which I call esse, has also the property that it is experienced. It asserts a necessary connexion between esse on the one hand and percipi on the other; these two words denoting each a distinct term, and esse denoting a term in which that denoted by percipi is not included. We have, then, in esse is percipi, a necessary synthetic proposition which I have undertaken to refute. And I may say at once that, understood as such, it cannot be refuted. If the Idealist chooses to assert that it is merely a self-evident truth, I have only to say that it does not appear to me to be so. But I believe that no Idealist ever has maintained it to be so. Although this—that two distinct terms are necessarily related—is the only sense which ‘esse is percipi’ can have if it is to be true and important, it can have another sense, if it is to be an important falsehood. I believe that Idealists all hold this important falsehood. They do not perceive that Esse is percipi must, if true, be merely a self-evident synthetic truth: they either identify with it or give as a reason for it another proposition which must be false because it is self-contradictory. Unless they did so, they would have to admit that it was a perfectly unfounded assumption; and if they recognised that it was unfounded, I do not think they would maintain its truth to be evident. Esse is percipi, in the sense
