The concept of knowledge is elusive – at least when epistemology starts scrutinizing the concept too much. According to Lewis's contextual epistemology, all there is to knowledge attribution in a given context is a set of rules for eliminating the relevant possibilities of error while succeeding over the remaining possibilities and properly ignoring the extravagant possibilities of error. Considering demons and brains as relevant possibilities of error is often what makes the concept of knowledge evaporate into thin air

Contextualistic epistemology starts much closer to home. Agents in their local epistemic environments have knowledge – and plenty of it in a variety of (conversational) contexts. Knowledge is not only possible, as counterfactual epistemology demonstrates, it is a real and fundamental human condition.

The general contextualistic template for a theory of knowledge is crisply summarized in DeRose's (1995) description of the attribution of knowledge. The description also embodies many of the epistemological themes central to the contextualistic forcing strategy:

The incentive to take skeptical arguments to knowledge claims seriously is based on an exploitation of the way in which otherwise operational epistemic concepts, notably knowledge, can be gravely disturbed by sudden changes of the linguistic context in which they figure.