Richard Foley

: Plato’s instructions entail that the line of Republic VI is divided so that the middle two segments are of equal length. Yet I argue that Plato’s elaboration of the significance of this analogy shows he believes that these segments are of unequal length because the domains they represent are not of equally clear mental states, nor perhaps of objects of equal reality. I label this inconsistency between Plato’s instructions and his explanation the “overdetermination problem.” The overdetermination problem has been a perennial concern, and a substantial amount of work has been produced which attempts to deal with it. I offer a classification of approaches to the overdetermination problem as a way of documenting the problem’s significance, and show why these approaches are all inadequate as solutions. My novel resolution of the overdetermination problem rests upon a demonstration that the contradiction is intentional. The later recapitulation of the ratio at 534a reveals that Plato was himself aware that the middle two segments are equal. I argue that this contradiction is a sophisticated device designed to lead the reader of the Republic through the four epistemic stages represented by the line itself. Most significantly, recognition of this mathematical contradiction acts as a goad, spurring independent philosophical reflection just in the way that Plato advocates in the Republic more generally

In this new book, Foley defends an epistemology that takes seriously the perspectives of individual thinkers. He argues that having rational opinions is a matter of meeting our own internal standards rather than standards that are somehow imposed upon us from the outside. It is a matter of making ourselves invulnerable to intellectual self-criticism. Foley also shows how the theory of rational belief is part of a general theory of rationality. He thus avoids treating the rationality of belief as a fundamentally different kind of phenomenon from the rationality of decision or action. His approach generates promising suggestions about a wide range of issues--e.g., the distinction between epistemic and non-epistemic reasons for belief; the question of what aspects of the Cartesian project are still worth doing; the significance of simplicity and other theoretical virtues; the relevance of skeptical hypotheses; the difference between a theory of rational belief and a theory of knowledge; the difference between a theory of rational belief and a theory of rational degrees of belief; and the limits of idealization in epistemology.

Many interpretations of Hume’s Dialogues Concerning Natural Religion have labored under the assumption that one of the characters represents Hume’s view on the Design Argument, and Philo is often selected for this role. I reject this opinion by showing that Philo is inconsistent. He offers a decisive refutation of the Design Argument, yet later endorses this very argument. I then dismiss two prominent ways of handling Philo’s reversal: first, I show that Philo is not ironic either in his skepticism or in his theistic reversal. Second, I reject the suggestion that the Design Argument is a natural belief, since it differs significantly from causal and external world beliefs. Finally, I argue that the control the Design Argument exerts is the product of a youthful indoctrination that prevents Philo from consistently maintaining his skeptical position.

One of the advantages of classical foundationalism was that it was thought to provide a refutation of skeptical worries, which raise the specter that our beliefs might be extensively mistaken. The most extreme versions of these worries are expressed in familiar thought experiments such as the brain-in-a-vat hypothesis, which imagines a world in which, unbeknownst to you, your brain is in a vat hooked up to equipment programmed to provide it with precisely the same visual, auditory, tactile, and other sensory inputs that you have in this world. As a result, your opinions about your immediate environment are the same as they are in this world. You have the same beliefs about your recent activities, your current physical appearance, your present job, and so on, but in fact you are a brain in a vat tucked away in a corner of a laboratory. Thus, in the brain-in-a-vat world, your beliefs about these everyday matters are mistaken, and mistaken not just in detail, but deeply mistaken.