Objective Knowledge

Explanatory knowledge consists of statements. Statements are at least in part explicit. Therefore inexplicit explanatory knowledge is not possible.

Entirely explicit explanatory knowledge is not possible either, as all knowledge refers to other knowledge implicitly.

Popper counters this criticism with two thought experiments (107-108).

First, if all our machines and tools were destroyed, and so were our subjective knowledge of how to use them, but libraries were not, then we could re-learn to use them by reading books.

Second, if all libraries were also destroyed, we couldn’t re-learn from books. Civilization wouldn’t re-emerge for millennia.

Therefore, Popper argues, world 3 is important and real.

According to Popper (ibid), opponents of world 3 “usually say that all these entities are, essentially, symbolic or linguistic expressions of subjective mental states”, that they’re merely, “means of communication…”

Popper says there are three worlds (OK 107):

I suggest…that there are physical worlds and a world of states of consciousness, and that these two interact. And I believe that there is a third world…
Among the inmates of my ‘third world’ are, more especially, theoretical systems; but inmates just as important are problems and problem situations. And I will argue that the most important inmates of this world are critical arguments, and what may be called—in analogy to a physical state or to a state of conscious- ness—the state of a discussion or the state of a critical argument; and, of course, the contents of journals, books, and libraries.

Key source on this topic: Karl Popper, Objective Knowledge: An Evolutionary Approach.

My specific edition is from 1994, Oxford University Press, New York. I’ll simply call it OK in this discussion.

Does it exist?

Knowledge can exist outside any mind. A book contains knowledge whether or not anyone reads it.