Abstract
In this chapter, we defend an explanationist version of proper functionalism. After explaining proper functionalism’s initial appeal, we note two major objections to proper functionalism: creatures with no design plan who appear to have knowledge (Swampman) and creatures with malfunctions that increase reliability. We then note how proper functionalism needs to be clarified because there are cases of what we call warrant-compatible malfunction. We then formulate our own view: explanationist proper functionalism, which explains the warrant-compatible malfunction cases and helps to block the above objections. We also advance a positive argument for explanationist proper functionalism.