WE MIGHT BEGIN with the sort of scene Descartes describes in the first of his Meditations: himself, seated in a dressing gown by a fire, holding a sheet of paper in his hand, wondering about the reality of that paper, his body, perhaps ultimately himself. It is tempting to see this scene as representative, in many ways, of what philosophy in his time is all about. To begin with, there is the emphasis on ordinary, everyday situations. Secondly, there is the effort to resolve questions that arise from reflection on such situations without having recourse to unwarranted assumptions or concepts that do not derive directly from the situation itself. Instead, we find each question pursued to its natural outcome through a method based on deductions and inferences. Finally, there is a concern with the ultimate purpose of such questions, a desire to ascertain whether they are in fact genuinely meaningful.
For all their immediate appeal, nevertheless, we now find ourselves at some distance from the various exemplary instances of Enlightenment philosophy. To some extent, the questions they asked have ceased to engage our energies, and even when they do, we no longer pursue them in the same way. Precisely because of this, however, I believe we should now be in a better position to arrive at new insights into the nature of some of the different modes of Enlightenment rationality. What I attempt to offer here, then, is an analysis of what several of these modes of Enlightenment rationality involve. Specifically, I focus on the sequence of thoughts or positions put forward by a particular philosophical text, in the belief that what is crucial to a given mode of philosophical rationality is the sequence of steps by which it undertakes to substantiate its thesis. Hence my use of Descartes Meditations as a kind of model for my study. Like Descartes, I present, at the beginning of each chapter, a problem that the ensuing analysis attempts to resolve by means of a sequence of deductions and inferences, in a style designed to reflect that of the text on which my discussion is based. Unlike Descartes, however, what I then proceed to show is how the use of such a method leads to unavoidable contradictions. By examining the precise ways in which these contradictions arise, finally, I try to