Contextualism, also known as epistemic contextualism, is a family of views in philosophy which emphasize the context in which an action, utterance, or expression occurs. Proponents of contextualism argue that, in some important respect, the action, utterance, or expression can only be understood relative to that context. Contextualist views hold that philosophically controversial concepts, such as "meaning P", "knowing that P", "having a reason to A", and possibly even "being true" or "being right" only have meaning relative to a specified context. Other philosophers contend that context-dependence leads to complete relativism.

In ethics, "contextualist" views are often closely associated with situational ethics, or with moral relativism.

Contextualism in architecture is a theory of design where modern building types are harmonized with urban forms usual to a traditional city.

In epistemology, contextualism is the treatment of the word 'knows' as context-sensitive. Context-sensitive expressions are ones that "express different propositions relative to different contexts of use". For example, some terms generally considered context-sensitive are indexicals, such as 'I', 'here', and 'now'; while 'I' has a constant linguistic meaning in all contexts of use, whom it refers to varies with context. Similarly, epistemic contextualists argue that the word 'knows' is context sensitive, expressing different relations in some different contexts.

Contextualism was introduced, in part, to undermine skeptical arguments that have this basic structure:

The contextualist solution is not to deny any premise, nor to say that the argument does not follow, but link the truth value of (3) to the context, and say that we can refuse (3) in context—like everyday conversational context—where we have different requirements to say we know.

The main tenet of contextualist epistemology is that knowledge attributions are context-sensitive, and the truth values of "know" depend on the context in which it is used. A statement like 'I know that I have hands' would be false. The same proposition in an ordinary context—e.g., in a cafe with friends— would be truth, and its negation would be false. When we participate in philosophical discourses of the skeptical sort, we seem to lose our knowledge; once we leave the skeptical context, we can truthfully say we have knowledge.

That is, when we attribute knowledge to someone, the context in which we use the term 'knowledge' determines the standards relative to which "knowledge" is being attributed (or denied). If we use it in everyday conversational contexts, the contextualist maintains, most of our claims to "know" things are true, despite skeptical attempts to show we know little or nothing. But if the term 'knowledge' is used when skeptical hypotheses are being discussed, we count as "knowing" very little, if anything. Contextualists use this to explain why skeptical arguments can be persuasive, while at the same time protecting the correctness of our ordinary claims to "know" things. This theory does not allow that someone can have knowledge at one moment and not the other, which would not 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.