This book is designed to explain the technical ideas that are taken for granted in much contemporary philosophical writing Notions like 'denumerability' 'modal scope distinction' ' Bayesian conditionalization' & 'logical completeness' are usually only elucidated deep within difficult specialist texts By offering simple explanations that by-pass much irrelevant & boring detail Philosophical Devices is able to cover a wealth of material that is normally only available to specialists The book contains four sections each of three chapters The first section is about sets & numbers starting with the membership relation & ending with the generalized continuum hypothesis The second is about analyticity a prioricity & necessity The third is about probability outlining the difference between objective & subjective probability & exploring aspects of conditionalization & correlation The fourth deals with metalogic focusing on the contrast between syntax & semantics an