According to the 2015 TOK Course Guide a Knowledge Claim is:

something that the claimant believes to be true, yet is also open to discussion and debate. It is therefore important that a knowledge claim is something that we believe we know and that we want to assess the validity of.

There are two different types of knowledge claims—the first type is claims about the world, and the second type is claims about knowledge.

• An example of a claim about the world is: “Hydrogen is the lightest chemical element.”
• An example of a claim about knowledge is: “The knowledge that hydrogen is the lightest chemical element is quite secure because the methods of chemistry give us a fairly good model of what chemical elements look like.”

This second claim is a claim about the reliability of the methods of chemistry itself, not about hydrogen. It is therefore a claim about knowledge, or a “second order knowledge claim”. Theory of Knowledge is much more interested in this type of claim.

According to the 2015 TOK Course Guide a Knowledge Question is:

an open question about knowledge. It sounds simple but this innocent sounding statement contains a couple of important subtleties.

First, the question is open in the sense that there are a number of plausible answers to it. The question is contestable. Dealing with open questions is a feature of TOK. Many students encountering TOK for the first time are struck by this apparent difference from many of the other classes in their school experience. Many find the lack of a single ‘right’ answer slightly disorienting. Nevertheless, knowledge questions underlie much of the knowledge that we take for granted. Much of the disagreement and controversy encountered in daily life can be traced back to a knowledge question. An understanding of the nature of knowledge questions can allow a deeper understanding of these controversies.

But there is a second point that is worth unpacking. Knowledge questions are about knowledge. That is, they are not questions of knowledge themselves but instead focus on the methods and mechanisms that produce knowledge – in TOK terminology they focus on ways of knowing and knowledge frameworks. In this sense knowledge questions are a little different from many of the questions dealt with in the subject classrooms. They are second order questions.