1. Epistemology: the study of the nature, source, limits, & justification of knowledge Skepticism: doubt that knowledge is possible • Taoism: the differentiation of things is relative; all things are really one • Pyrrhonism: we should refuse to make dogmatic claims to know because all knowledge is relative Chuang Tzu(369-286 BCE) Sextus Empiricus (2nd Century)

2. Cartesian Doubt René Descartes (1596-1650) • Sense experiences are often wrong • I might be wrong about whether I have a body or if there is a world apart from my imagination (it may be a dream) • I might be wrong even about whether my reasoning abilities (e.g., 2+3=5) can be trusted (evil genius); so I should suspend judgment

3. Objectionsto Descartes’ Method of Doubt • To think some experiences are wrong is to assume that some are right • To doubt everything, we must doubt whether we are truly doubting, and that requires us to assume a public world of language users • Limiting knowledge only to what we know with certainty is too restrictive: we often know things not based on indubitable foundations

4. Hume: Skepticism about the External World • The continued existence of things apart from our experience cannot be known, for we cannot compare our experience (or self) with anything outside it as its supposed cause • Problem of induction: we cannot say that something is probable without assuming that the future will resemble the past • Induction itself is unjustifiable (Strawson)