Epistemology Cheat Sheet
The core ideas of Epistemology distilled into a single, scannable reference — perfect for review or quick lookup.
Quick Reference
Justified True Belief
The classical definition of knowledge, originating with Plato, which holds that knowledge is a belief that is both true and supported by adequate justification or evidence. A person knows a proposition if and only if the proposition is true, the person believes it, and the person is justified in believing it.
The Gettier Problem
A challenge posed by Edmund Gettier in 1963 showing that justified true belief is not sufficient for knowledge. Gettier presented cases in which a person has a justified true belief that intuitively does not count as knowledge because the justification connects to the truth only by luck.
Rationalism
The epistemological position that reason, rather than sensory experience, is the primary source of knowledge. Rationalists hold that certain truths can be known a priori through the exercise of pure reason and that the mind possesses innate ideas or principles not derived from experience.
Empiricism
The epistemological position that sensory experience is the primary source of knowledge. Empiricists argue that the mind begins as a blank slate (tabula rasa) and that all concepts and knowledge are ultimately derived from what we perceive through our senses.
Skepticism
The epistemological position that questions or denies the possibility of certain or complete knowledge. Skeptics argue that our cognitive faculties, evidence, or methods may be insufficient to yield genuine knowledge about the external world, other minds, or certain domains.
A Priori vs. A Posteriori Knowledge
A priori knowledge is knowledge that can be acquired independently of experience, through reason alone (e.g., logic and mathematics). A posteriori knowledge is knowledge that requires experience or empirical observation to be obtained (e.g., scientific facts).
Foundationalism
The view that knowledge is structured like a building, resting on a foundation of basic or self-evident beliefs that do not require further justification. All other beliefs are justified by being derived from or supported by these foundational beliefs.
Coherentism
The theory of justification that holds a belief is justified if and only if it coheres with a system of mutually supporting beliefs. Unlike foundationalism, coherentism denies that there are any privileged basic beliefs; instead, justification is a matter of how well beliefs fit together.
Epistemic Justification
The concept of having adequate reasons, evidence, or grounds for holding a belief. Epistemic justification is a central requirement for knowledge and distinguishes reasoned beliefs from lucky guesses. Theories of justification include internalism (justification depends on factors accessible to the believer) and externalism (justification can depend on external factors).
Reliabilism
An externalist theory of justification holding that a belief is justified if it is produced by a reliable cognitive process, one that tends to produce true beliefs. The believer need not have access to or awareness of why the process is reliable.
Key Terms at a Glance
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