In Epistemology 'knowledge' is traditionally defined as composed of thee essential elements: beliefs, which are true, and which can be justified (or, true, justified, belief).

While this is the definition we will use in our courses it should be noted that significant objections have been raised against this account of knowledge, most notably by Edmund Gettier. In his now famous 1963 article "Is Justified True Belief Knowledge?" Gettier poses two counter examples which seem to show the traditional analysis of knowledge is in need of revision.