This book puts forward an interpretation of rationality which is much broader than the one underlying the current polarity between analytic and continental philosophy. It will help to reaffirm a range of ideas which have long been pushed to the sidelines by the dominance of the geometric model of philosophical argument.Descartes's dream of attaining a `certitude equal to the demonstrations of Arithmetic and Geometry' reinforced the assumption that rationality must be assessed in terms of logical structure. Against this, Pascal invoked the notion of `finesse', and Warner extends Pascal's usage in this book to specify a related set of informal but legitimate styles of argument.