I.

Introduction

Skepticism (Greek skeptesthai, “to examine”), in philosophy, doctrine that denies the possibility of attaining knowledge of reality as it is in itself, apart from human perception. By gradual extension of its meaning, the word skepticism has also come to signify doubt about what is generally accepted as true. All philosophical skepticism is ultimately epistemological; that is, it is based on views about the scope and validity of human knowledge (see Epistemology).