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).