except observation, we should say that, if observation gives no reason for asserting it, we have _no_ reason for asserting it; and having no reason for asserting this connection between the perceived and the unperceived, we should say that we have none either for asserting the even probable existence of the unperceived. This, I think, is what we commonly mean by saying that we have no reason to believe in the existence of a particular thing which we do not perceive. And hence, I think, those philosophers who hold that our own observations give us no reason whatever for any generalisation whatever concerning the connection of any of them with those of other people, are quite right in concluding that we have no reason to assert that any other person ever did have any particular thought or perception whatever. I think that the words of this conclusion, understood in their natural meaning, express precisely what the premiss asserts. We need not, indeed, conclude, as many of these philosophers are inclined to do, that, because we have no reason for believing in the existence of other people, it is therefore highly doubtful whether they do exist. The philosophers who advocate this opinion commonly refute themselves by assigning the existence of other people as part of their reason for believing that it is very doubtful whether any other people exist. That for which we have no reason may, nevertheless, be certainly true. And, indeed, one of the philosophers who hold most clearly and expressly that we do know not only the existence of other people but also that of material objects, is also one of those who deny most emphatically that our own observations can give any reason for believing either in the one or in the other. I refer to Thomas Reid. Reid, indeed, allows himself to use not only the word "observe," but even the word "perceive," in that wide sense in which it might be said that we observe or perceive the thoughts and feelings of others: and I think that the fact that he uses the words in this sense, has misled him into thinking that his view is more plausible and more in accordance with Common Sense than it really is: by using the words in this sense he is able to plead that "observation" really does give a reason for some of those generalisations, for which Common Sense holds that "observation" (in a narrower sense) does give a reason. But with regard to what we observe or perceive, in the strict sense to which 1 am confining those words, he asserts quite explicitly that it gives us no reason either for believing in the existence of material objects or for believing in the existence of other minds. Berkeley, he says, has proved incontrovertibly that it gives us no reason for the one, and Hume that it gives us no reason for the other.