Epistemology is the study of knowledge - its nature, sources, limits, and criteria.

A priori knowledge is knowledge that is independent of experience (e.g. logical, mathematical truths). A posteriori knowledge is knowledge derived from experience or empirical evidence.

The problem of hard data refers to whether sense data (e.g. sights, sounds) can be considered truly reliable data about the external world, given the potential for illusion or hallucination.

The Gettier problem challenges the classical definition of knowledge as justified true belief, by presenting thought experiments where someone has a justified true belief that does not constitute knowledge.

Foundationalism is the view that some beliefs or propositions are basic and self-justifying, and all other justified beliefs derive their justification from these basic beliefs.

Coherentism is the view that justification of belief derives from the coherence or consistent relationships beliefs have with each other, rather than deriving from self-evident basic beliefs.

The Münchhausen trilemma argues that efforts to ground knowledge on a consistent foundation lead to a trilemma - infinite regress, circularity, or dogmatism - making a complete foundation impossible.

The Cartesian circle arises when Descartes attempts to use the clarity and distinctness of his perceptions as a basis for knowledge, while also arguing that God's existence must be known clearly and distinctly first in order to trust his perceptions.

Epistemic contextualism is the view that the standards for what constitutes knowledge can vary based on the specific context or situation one is in.

The Agrippa trilemma argues that any effort to provide a rational justification for knowledge leads to one of three alternatives - infinite regress, circularity, or dogmatism - presenting a challenge for theories of justification.

Fallibilism is the view that no belief or knowledge claim can be held with complete certainty, and all claims are subject to possible revision based on new evidence or reasoning.

The Quine-Duhem thesis argues that it is impossible to test scientific theories in isolation, as any failed prediction could be due to the theory itself or to background beliefs and auxiliary hypotheses.

Virtue epistemology focuses on the intellectual virtues or character traits, like open-mindedness or intellectual humility, that enable good cognition rather than just focusing on properties of beliefs themselves.

The Gettier problem challenges the classical definition of knowledge as justified true belief, by presenting thought experiments where someone has a justified true belief that does not constitute knowledge.

Foundationalism is the view that some beliefs or propositions are basic and self-justifying, and all other justified beliefs derive their justification from these basic beliefs.

Coherentism is the view that justification of belief derives from the coherence or consistent relationships beliefs have with each other, rather than deriving from self-evident basic beliefs.

The Münchhausen trilemma argues that efforts to ground knowledge on a consistent foundation lead to a trilemma - infinite regress, circularity, or dogmatism - making a complete foundation impossible.

The Cartesian circle arises when Descartes attempts to use the clarity and distinctness of his perceptions as a basis for knowledge, while also arguing that God's existence must be known clearly and distinctly first in order to trust his perceptions.

Epistemic contextualism is the view that the standards for what constitutes knowledge can vary based on the specific context or situation one is in.

The Agrippa trilemma argues that any effort to provide a rational justification for knowledge leads to one of three alternatives - infinite regress, circularity, or dogmatism - presenting a challenge for theories of justification.

Fallibilism is the view that no belief or knowledge claim can be held with complete certainty, and all claims are subject to possible revision based on new evidence or reasoning.

The Quine-Duhem thesis argues that it is impossible to test scientific theories in isolation, as any failed prediction could be due to the theory itself or to background beliefs and auxiliary hypotheses.

Virtue epistemology focuses on the intellectual virtues or character traits, like open-mindedness or intellectual humility, that enable good cognition rather than just focusing on properties of beliefs themselves.

Internalism holds that all justifying reasons for belief must be internal to the mind of the believer. Externalism allows that beliefs can be justified by external factors beyond the believer's mind.

Epistemic relativism is the view that truth and knowledge are relative to particular contexts, frameworks or perspectives, rather than being absolute or universal.

According to empiricism, the main sources of knowledge are sense experience and inductive inferences from sensory data.

The problem of induction, raised by Hume, questions the rational justification for inductive reasoning and generalizing from past observations to make predictions about the future or unobserved cases.

The problem of the criterion asks how we can establish criteria or standards for knowledge if we cannot make use of any knowledge claims until such criteria have been established, creating a circularity.

Reliabilism is the view that a belief is justified or qualifies as knowledge if it is acquired by a reliable belief-forming process, faculty or method, such as perception, memory or induction.

Closure principles govern how knowledge transmits across competent deductions. Underdetermination refers to the idea that evidence always underdetermines theory, allowing multiple theories to fit the same data.

Dogmatism is an unjustified certainty in beliefs. Skepticism is a doubting or denial of the possibility of knowledge, at least of a certain domain or kind.

The Duhem-Quine thesis states that it is impossible to test a scientific theory in isolation because any failed prediction could be due to the theory itself or to background assumptions.

A priori knowledge is knowledge independent of experience, such as logical and mathematical truths. A posteriori knowledge is knowledge derived from experience or empirical evidence.

Propositional knowledge is knowledge of truths or facts. Knowledge by acquaintance is direct, non-propositional awareness or familiarity with objects, sensations or oneself.

The regress problem questions how any belief or proposition can be justified given that any justification itself requires further justification, leading to an infinite regress.

Internalist theories hold that all justifying reasons must be internal mental states accessible to the believer. Externalist theories allow that beliefs can be justified by external factors beyond just the believer's mind.

Naturalized epistemology, advocated by Quine, seeks to reformulate epistemological questions as psychological or empirical questions, studied using scientific methods rather than a priori conceptual analysis.

Pyrrhonian skepticism, based on the philosophy of Pyrrho, is an ancient Greek form of skepticism that suspends judgment about all philosophical views and denies the possibility of attaining truth.

The sorites paradox arises when attempting to provide precise boundaries or definitions for vague concepts like knowledge, questioning how much justification or truth is required for knowledge.

The value problem questions why knowledge is more valuable than merely true belief, given that both are equally useful for practical purposes.

Semantic theories define truth in terms of relations between language and the world. Epistemic theories define truth in terms of the criteria or evidence required to justifiably believe something.

Fallibilism is the view that our knowledge claims and beliefs cannot be absolutely certain, and may require revision in light of new evidence or reasoning.

Holistic coherentism is the view that a belief is justified not by coherence with other beliefs alone, but by the overall coherence of the entire belief system.

The Preface Paradox arises when an author asserts confidence in each individual claim in a book, yet also expresses doubt that the book contains no errors, apparently contradicting themselves.

Epistemic injustice refers to unfair deficits in credibility and capacity to convey knowledge, due to prejudices against the speaker's identity or social position.

A de dicto belief attributes a property to an object by way of a description or sense. A de re belief is a belief directly about the object itself.

The problem of forgotten evidence questions whether justification requires retaining all the evidence that initially justified a belief, given we often forget initial justifying factors.

The Zeno Paradox poses challenges to our understanding of motion, space and time that relate to broader skepticism about the reliability of sense perception and reason.

Modest foundationalism holds some non-inferential beliefs are properly basic. Radical foundationalism holds all non-inferential beliefs formed properly are properly basic.

Kuhn's incommensurability thesis argues that succeeding scientific paradigms are incommensurable or cannot be perfectly translated into or understood from the perspective of the preceding paradigm.