Chisholm uses the word diallelus to describe the problem of the criterion (a skeptical problem):
that we can only know what is knowledge via a criteria,
we can only set the criteria by analyzing knowledge
Chisholm’s ‘wheel’ argument is circular rather than regressive. Chisholm breaks into two questions:
A) What do we know? what is the extent of our knowledge?
B) How are we to decide whether we know? What are the criteria of our knowledge?
“We can formulate the position of the skeptic on these matters. He will say: ‘you cannot answer question A until you have answered question B. And you cannot answer question B until you have answered question A. Therefore you cannot answer either question. You cannot know what, if anything, you know, and there is no possible way to decide in any case.'” (Chisholm in ‘The Problem of Criterion’ p66)
Methodism: to approach the problem from a establishing a set of criteria. The problem here, according to Chisholm is that the criteria will be arbitrary. Without knowing what what you know, the criteria has no limits, could be anything as it does not know what it is aiming at.
Particularism: Chisholm’s preferred position. The particularist will start with two uncontroversial pieces of knowledge: ‘I have two hands.’ You can now identify a criteria that reflect the features of these basic pieces of knowledge. We’re not trying to show that we have knowledge, but rather how.