Abstract

My dissertation is an examination of the epistemic grounds of claims concerning what is possible or necessary. It is often suggested that we can determine whether a state of affairs is possible by appeal to our ability to conceive of the state of affairs. A state of affairs is possible if conceivable; impossible if inconceivable. Likewise, it is sometimes suggested that consistency provides the key to modal knowledge. In the first two chapters I carefully distinguish a number of different interpretations of these crucial notions of conceivability and consistency. I argue that, on any reading, neither conceivability nor consistency provides an adequate guide by which we can tell what is possible. I defend the controversial claim that we can know what is possible be reliance upon modal intuitions. The bulk of my dissertation is an attempt to explicate just what such intuitions amount to, and to account for their positive epistemic status. I draw upon discussions of moral, mathematical and logical, and empirical intuitions. What emerges is a modest account of modal intuitions as the products belief-forming mechanisms which are such that simply reflecting upon some modal propositions results in a strong, at times irresistible, inclination towards belief. Neither infallibility, indubitability, nor incorrigibility are claimed for all intuitive modal beliefs. I focus upon the problem of accounting for the reliability of these modal intuitions given the fact that unlike our perceptions of the external world, it seems there could be no causal link between intuitions and "the modal facts of the matter." I argue that trusting one's intuitions is consonant with doing one's best to believe truths and avoid falsehoods. I also argue that intuitions can, indeed, result in knowledge of necessary truths, even in the absence of any causal link to abstract modal truths. In the final chapter I apply the conclusions I have drawn to two specific issues: The Cartesian argument for dualism based on the apparent imaginability of mind without body, and a criticism of the Anselmian conception of God, based on our ability to conceive of worlds without such a being.