5. Inquiry

On the theory of this book, if something is known, it is available to use as a starting point in inquiry. It is natural to move from that view to the view that it is irrational to inquire into what one already knows. But recent work on inquiry shows that this isn’t right; depending on what one wants to do in an inquiry one may want to deliberately set aside some things one knows. And that might mean inquiry into what one already knows, what we ordinarily call double-checking, is reasonable. This fact is used to respond to an influential objection by Jessica Brown to the style of argument I use in chapter 2.