Abstract

It seems undeniable that we have many items of modal knowledge. Tradition has it that conceivability is the evidence for possibility that gets us to this modal knowledge. But "conceive" cannot mean think, understand, entertain, suppose, or find believable, because none of these are suited to serve as evidence for possibility, and if it is none of these, it is mysterious what conceivability is, and why it is evidence for possibility. I argue that sensory imagination is the most promising candidate for a source of modal evidence. A theory of imaginative content is developed in Chapter One, one which allows what seems undeniable: that we do imagine the impossible. This raises a challenge to explain why, in the face of our ability to imagine the impossible, we should accept imagination as modal evidence. The predominant response, developed by Saul Kripke, limits the scope of imagination to preserve the link between imagination and what is possible. In Chapter Two I argue that the Kripkean theory is best thought of as an error theory: when we take ourselves to imagine, e.g., water without H2O, or Mark Twain and Sam Clemens in a fistfight, we are mistaken. I articulate and defend an alternative modal epistemology, one that exploits the crucial difference between assigned and basic content of imagining. The evidential value of some imaginings is undermined by independent considerations about the connection between assigned content and ignorance. Instances in which we imagine the impossible are all cases where these independent considerations give us reason to doubt the imagining's value as modal evidence. The conclusions about assigned content are applied in Chapter Three to the first-person imaginings thought to be crucial in philosophy of mind: the imaginability of zombies, and the imaginability of being a disembodied soul. It is argued that such imaginings offer no evidence favoring dualism over materialism. Finally, alternatives to imagination as the source for modal evidence are discussed in Chapter Four. I explore both direct intuition and a priori-based accounts, and conclude that neither offers a genuine alternative to the imagination