Abstract
Medieval philosophers presented Gettier-type objections to the commonly accepted view of knowledge as firmly held true belief, and formulated additional conditions that meet the objections or analyzed knowledge in a way that is immune to the Gettier-type objections. The proposed conditions can be divided into two kinds: backward-looking conditions and forward-looking conditions. The former concern an inquirer’s current belief system and the way the inquirer acquired her beliefs, the latter refer to what the inquirer may come to learn in the future and how she can respond to objections. Some conditions of knowledge proposed in late nineteenth- and twentieth-century epistemology can be regarded as variants of the conditions put forward by medieval authors.