In ethics, "contextualist" views are often closely associated with situational ethics, or with moral relativism. (see Timmons 1998).
The main tenet of contextualist epistemology, no matter what account of knowledge it is wedded to, is that knowledge attributions are context-sensitive. That is, when we attribute knowledge to someone, what matters is the context in which we use the term 'knowledge'. If we use it in everyday conversational contexts, the contextualist maintains, we can save most of the knowledge we think we have from skeptical hypotheses. If the term 'knowledge' is used when skeptical hypotheses are being considered, then the utterances regarding knowledge that a person has are false. It is important to note that this theory does not allow that someone can have knowledge at one moment and not the other, for this would hardly be a satisfying epistemological answer. What contextualism entails is that in one context an utterance of a knowledge attribution can be true, and in a context with higher standards for knowledge, the same statement can be false. This happens in the same way that 'I' can correctly be used (by different people) to refer to different people at the same time.
Thus, the standards for attributing knowledge to someone, the contexualist claims, vary from one user's context to the next. Thus, if I say "John knows that his car is in front of him", the utterance is true if and only if (1) John believes that his car is in front of him, (2) the car is in fact in front of him, and (3) John meets the epistemic standards that my (the speaker's) context selects. This is a loose contextualist account of knowledge, and there are many significantly different theories of knowledge that can fit this contextualist template and thereby come in a contextualist form.
For instance, an evidentialist account of knowledge can be an instance of contextualism if it's held that strength of justification is a contextually varying matter. And one who accepts a relevant alternatives account of knowledge — on which c — can be a contextualist by holding that what range of alternatives are relevant is sensitive to conversational context. DeRose adopts a type of modal or "safety" (as it has since come to be known) account on which knowledge is a matter of one's belief as to whether or not p is the case matching the fact of the matter, not only in the actual world, but also in the sufficiently close possible worlds: Knowledge amounts to there being no "nearby" worlds in which one goes wrong with respect to p. But how close is sufficiently close? It's here that DeRose takes the modal account of knowledge in a contextualist direction, for the range of "epistemically relevant worlds" is what varies with context: In high standards contexts one's belief must match the fact of the matter through a much wider range of worlds than is relevant to low standards contexts.
However, contextualist epistemology has been criticized by several philosophers. Contextualism is opposed to any general form of Invariantism, which claims that knowledge is not context-sensitive (i.e. it is invariant). More recent criticism has been in the form of rival theories, including Subject-Sensitive Invariantism (SSI), mainly due to the work of John Hawthorne (2004), and Interest-relative Invariantism (IRI), due to Jason Stanley (2005). SSI claims that it is the context of the subject of the knowledge attribution that determines the epistemic standards, whereas Contextualism maintains it is the attributor. IRI, on the other hand, argues that it is the context of the practical interests of the subject of the knowledge attribution that determines the epistemic standards. Stanley writes that bare IRI is "simply the claim that whether or not someone knows that p may be determined in part by practical facts about the subject's environment. ("Contextualism" is a misnomer for either form of Invariantism, since "Contextualism" among epistemologists is considered to be restricted to a claim about the context-sensitivity of knowledge attributions (or the word "knows"). Thus, any view which maintains that something other than knowledge attributions are context-sensitive is not, strictly speaking, a form of Contextualism.)
An alternative to contextualism called contrastivism has been proposed by Jonathan Schaffer. Contrastivism, like contextualism, uses semantic approaches to tackle the problem of skepticism