Does Knowledge require denotation?

An interesting question, Anon. Denotation means many related things, in different disciplines, and in all of them, I believe the answer is no. Denotation is a not a sufficient prerequisite for knowledge.

Going through Denotation:

• In linguistics and semiotics, knowing the denotation/sense of a word is knowing only a narrow subset of its meaning: you also need to know its connotative, emotional meaning to know how the word works in context. Knowing that assertive and bossy refer to the same kind of attitude doesn’t mean you know how to use them appropriately.
• In logic, we can go further: the denotation as the extension/sense of a word, the set of all things to which a word applies, is an unworkably narrow kind of meaning. To use the hackneyed example, the Morning Star and the Evening Star have two different senses, even if they both refer to {Venus}. The Present King of France and the President of Australia have different senses, even if their denotation is the null set in both cases.
• In fact, inasmuch as the Present King of France and the President of Australia don’t have a denotation (a set of things they refer to in the world), denotation isn’t even a necessary component of meaning—and therefore of knowledge as the destination of meaning. You can know about things that don’t exist—and which therefore have no denotation.