Epistemology

Since Plato, philosophers have defined knowledge as "justified true belief" — a belief that is both true and held for good reasons. This tripartite definition seemed satisfactory until 1963, when Edmund Gettier published a short paper that devastated it. Gettier cases are situations where someone has a justified true belief that nevertheless seems not to count as knowledge.

The simplest Gettier case: you look at a clock that has stopped, and it reads 3:15. It is currently 3:15. Your belief that it is 3:15 is true, and you are justified in holding it (clocks are usually reliable). But intuitively, you don't know it's 3:15 — you got lucky. The standard definition is wrong.

The response to Gettier has occupied epistemologists for six decades. Proposals include: add a "no false lemmas" condition; require "sensitivity" (the belief tracks truth counterfactually); require "safety" (in nearby possible worlds, if you believe it, it's true); require a reliable causal connection between the fact and the belief (reliabilism). None of these proposals has achieved consensus, and the quest to define knowledge continues.

Skepticism — the view that we know much less than we think, or perhaps nothing at all — has been a permanent philosophical challenge. Descartes' skeptical hypotheses (the evil demon, the dream argument) pushed skepticism to its extreme: for all I know, all my beliefs are false, implanted by a powerful deceiving agent. The interesting philosophical question is not whether Descartes' demon is real but whether we could ever have the resources to rule it out.

Contextualism (DeRose, Cohen) offers an influential response: the standards for "knowing" shift with context. In everyday contexts, you know you have hands. In a philosophy seminar where skeptical hypotheses are being considered, the standard rises and you might not know. Knowledge attributions are context-sensitive, like "tall" — you can be tall for a child but not tall for a basketball player.

Reliabilism (Goldman) holds that a belief counts as knowledge if it was produced by a reliable belief-forming process — a process that tends to produce true beliefs. Perception, memory, inference, testimony are all (in normal circumstances) reliable. The skeptic's demon would have to interfere with these processes — but since it doesn't actually exist, our actual beliefs formed through actual reliable processes can count as knowledge.

Most of what any individual knows, she knows through testimony — the reports of others. I know that the Battle of Hastings was in 1066 not by having been there but because a chain of testimony stretches back to people who were. I know that evolution by natural selection is the best explanation of biological diversity not by having done the research but by trusting the testimony of biologists. Social epistemology examines the epistemic properties of social structures: when should we trust testimony? How does disagreement between experts affect our beliefs? What epistemic responsibilities do institutions have?

Miranda Fricker's concept of epistemic injustice has become influential: this occurs when someone suffers a wrong specifically in their capacity as a knower. Testimonial injustice happens when a speaker's credibility is unfairly reduced due to identity prejudice — the woman whose medical symptoms are dismissed, the Black man whose testimony is disbelieved. Hermeneutical injustice happens when a gap in collective interpretive resources puts someone at an unfair disadvantage — as when there was no concept of "sexual harassment" and those experiencing it couldn't name what was happening to them.