Blackwell Reference Online

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Epistemology, which is also called the theory of knowledge, is the branch of philosophy concerned with enquiry into the nature, sources and validity of knowledge. Among the chief questions it attempts to answer are: What is knowledge? How do we get it? Can our means of getting it be defended against sceptical challenge? These questions are implicitly as old as philosophy, although their first explicit treatment is to be found in P lato ( c. 427–347 bc ) (see chapter 23 ), in particular in his Theaetetus. But it is primarily in the modern era, from the seventeenth century onwards-as a result of the work of D escartes (1596–1650) ( chapter 26 ) and L ocke (1632–1704) ( chapter 29 ) in association with the rise of modern science-that epistemology has occupied centre-stage in philosophy. One obvious step towards answering epistemology's first question is to attempt a definition. The standard preliminary definition has it that knowledge is justified true belief. This definition looks plausible because, at the very least, it seems that to know something one must believe it, that the belief must be true, and that one's reason for believing it must be satisfactory in the light of some criterion-for one could not be said to know something if one's reasons for believing it were arbitrary or haphazard. So each of the three parts of the definition appears to express a necessary condition ... log in or subscribe to read full text