Thus although truth and falsehood are properties of beliefs, yet they are in a sense extrinsic properties, for the condition of the truth of a belief is something not involving beliefs, or (in general) any mind at all, but only the objects of the belief. A mind, which believes, believes truly when there is a corresponding complex not involving the mind, but only its objects. This correspondence ensures truth, and its absence entails falsehood. Hence we account simultaneously for the two facts that beliefs (a) depend on minds for their existence, (b) do not depend on minds for their truth. 
There are three points to observe in the attempt to discover the nature of truth, three requisites which any theory must fulfil.
(1) Our theory of truth must be such as to admit of its opposite, falsehood. A good many philosophers have failed adequately to satisfy this condition: they have constructed theories according to which all our thinking ought to have been true, and have then had the greatest difficulty in finding a place for falsehood. In this respect our theory of belief must differ from our theory of acquaintance, since in the case of acquaintance it was not necessary to take account of any opposite.
(2) It seems fairly evident that if there were no beliefs there could be no falsehood, and no truth either, in the sense in which truth is correlative to falsehood. If we imagine a world of mere matter, there would be no room for falsehood in such a world, and although it would contain what may be called ‘facts’, it would not contain any truths, in the sense in which truths are things of the same kind as falsehoods. In fact, truth and falsehood are properties of beliefs and statements: hence a world of mere matter, since it would contain no beliefs or statements, would also contain no truth or falsehood.
(3) But, as against what we have just said, it is to be observed that the truth or falsehood of a belief always depends upon something which lies outside the belief itself. If I believe that Charles I died on the scaffold, I believe truly, not because of any intrinsic quality of my belief, which could be discovered by merely examining the belief, but because of an historical event which happened two and a half centuries ago. If I believe that Charles I died in his bed, I believe falsely: no degree of vividness in my belief, or of care in arriving at it, prevents it from being false, again because of what happened long ago, and not because of any intrinsic property of my belief. Hence, although truth and falsehood are properties of beliefs, they are properties dependent upon the relations of the beliefs to other things, not upon any internal quality of the beliefs. [87-8]
The commonsense theory of knowledge, and with it all—or almost all—philosophers until at least Bolzano and Frege, took it for granted that there was only one kind of knowledge—knowledge possessed by some knowing subject.
I will call this kind of knowledge ‘subjective knowledge’, in spite of the fact that, as we shall see, genuine or unadulterated or purely subjective conscious knowledge simply does not exist.
The theory of subjective kowledge is very old; but it becomes explicit with Descartes: ‘knowing’ is an activity and presupposes the existence of a knowing subject. It is the subjective self who knows.
Now I wish to distinguish between two kinds of ‘knowledge’: subjective knowledge (which should better be called organismic knowledge, since it consist of the dispositions of organisms); and objective knowledge, or knowledge in the objective sense, which consists of the logical content of our theories, conjectures, guesses (and, if we like, of the logical content of our genetic code). 
As opposed to this, traditional epistemology is interested in the second world [World 2]: in knowledge as a certain kind of belief—justifiable belief, such as belief based upon perception. As a consequence, this kind of belief philosophy cannot explain (and dos not even try to explain) the decisive phenomenon that scientists criticize their theories and so kill them. Scientists try to eliminate their false theories, they try to let them die in their stead. The believer—whether animal or man—perishes with his false beliefs.