Perhaps, it may be thought that the fallacy involved in this argument is too gross for it to be possible that Mr. Bradley should have been guilty of it. But there are other passages in _Appearance and Reality_--particularly what he says about Error --which look to me as if he certainly was guilty of it. I suppose it will be quite obvious to everyone here that it is a fallacy; that the fact that we can think of unicorns is not sufficient to prove that, in any sense at all, there _are_ any unicorns. Yet, I am not sure that I know myself what is _the_ mistake involved in thinking that it _is_ sufficient, and I am going, therefore, to try to put as clearly as I can, what I think it is, in the hope that somebody may be able, if I am wrong, to correct me.
The main mistake, I suppose, is the mistake of thinking that the proposition "Unicorns are thought of" is a proposition of the same form as "Lions are hunted"; or the proposition "I am thinking of a unicorn" of the same form as "I am hunting a lion"; or the proposition "Unicorns are objects of thought" of the same form as "Lions are objects of the chase." Of the second proposition in each of these three pairs, it is in fact the case that it could not be true unless there were lions--at least one. Each of them does, in fact, assert both with regard to a certain property--which we will call that of "being a lion"--that there _are_ things which possess it, and also with regard to another--that of being hunted--that some of the things which possess the former possess this property too. But it is obvious enough to common sense that the same is by no means true of the _first_ proposition in each pair, in spite of the fact that their grammatical expression shows no trace of the difference. It is perfectly obvious that if I say "I am thinking of a unicorn,"
I am not saying both that there is a unicorn and that I am thinking of it, although, if I say "I am hunting a lion," I am saying both that there is a lion, and that I am hunting it. In the former case,
I am _not_ asserting that the two properties of being a unicorn and of being thought of by me both belong to one and the same thing; whereas, in the latter case, I am asserting that the two properties of being a lion and of being hunted by me _do_ belong to one and the same thing. It is quite clear that there is _in fact_, this difference between the two propositions; although no trace of it appears in their verbal expression. And why we should use the same form of verbal expression to convey such different meanings is more than I can say. It seems to me very curious that language, in this, as in the other instance which we have just considered of "Lions are real" and "Lions are mammalian," should have grown up just as if it were expressly designed to mislead philosophers; and I do not know why it should have. Yet, it seems to me there is no doubt that in ever so many instances it has. Moreover, _exactly_ what _is_ meant by saying "I am thinking of a unicorn" is not by any means clear to me. I think we can assert at least this: In order that this proposition should be true, it is necessary (1) that I should be conceiving, with regard to a certain property, the hypothesis that there Is something which possesses it, and (2) that the property in question should be such that, if anything did possess it there would be a unicorn. Although this is plainly true, it does not give us completely what is _meant_ by the statement, "I am thinking of a unicorn"; and I do not know what the complete meaning is. It is certainly _not_ that I am conceiving with regard to the property of "being a unicorn," that there is something which possesses it; since I may be thinking of a unicorn, without ever having conceived the property of "being a unicorn" at all. Whatever it does mean, the point which concerns us is that it is certainly _not_ necessary for its truth, that the property of being a unicorn should, in fact, belong to anything whatever, or, therefore, that there should in any sense whatever _be_ a unicorn. And the fallacy I am attributing to Mr. Bradley is that of supposing that, _in some sense,_ it must imply this latter.