'Knowledge issues' are derived from the concept of the 'Theory of Knowledge' (TOK). This extremely verbose academic subject includes some rhetorical questions like "What is the value of the distinction between what we know and what we don't know'. These are "issues" in context with TOK, which if taken to a laborious level equate to defining what is known and not known, and establishing values for each. Some critics question this approach, in this instance mainly on the basis of the logic of a concept which requires one to define what one does not know, to value it.