Definitions of knowledge

Some general features of knowledge are widely accepted among philosophers, for example, that it involves cognitive success and epistemic contact with reality.

Justification means that the belief fulfills certain norms like being based on good reasons or being the product of a reliable cognitive process.

This approach seeks to distinguish knowledge from mere true beliefs that arise from superstition, lucky guesses, or flawed reasoning.

Critics of the justified-true-belief view, like Edmund Gettier, have proposed counterexamples to show that some justified true beliefs do not amount to knowledge if the justification is not genuinely connected to the truth, a condition termed epistemic luck.

[6] On the theoretical side, on the other hand, there are so-called real definitions that aim to grasp the term's essence in order to understand its place on the conceptual map in relation to other concepts.

[6][10][11] Real definitions usually presume that knowledge is a natural kind, like "human being" or "water" and unlike "candy" or "large plant".

[7] For example, this is René Descartes's approach, who aims to find absolutely certain or indubitable first principles to act as the foundation of all subsequent knowledge.

[6][22] In this case, the skeptic only has to show that any putative knowledge state lacks absolute certainty, that while the actual belief is true, it could have been false.

This definition characterizes knowledge in relation to three essential features: S knows that p if and only if (1) p is true, (2) S believes that p, and (3) this belief is justified.

[23][24] Today, there is wide, though not universal, agreement among analytic philosophers that the first two criteria are correct, i.e., that knowledge implies true belief.

[1][8][7][4] For example, if someone believes that Machu Picchu is in Peru because both expressions end with the letter u, this true belief does not constitute knowledge.

The more common approach in the contemporary discourse is to allow fallible justification that makes the justified belief rationally convincing without ensuring its truth.

These states are usually understood as reasons or evidence possessed, like perceptual experiences, memories, rational intuition, or other justified beliefs.

Various problems with internalism have led some contemporary philosophers to modify the internalist account of knowledge by using externalist conceptions of justification.

[8][1] Externalists include factors external to the person as well, such as the existence of a causal relation to the believed fact or to a reliable belief formation process.

[5][39] In Plato's Theaetetus, Socrates considers a number of theories as to what knowledge is, first excluding merely true belief as an adequate account.

[23][24] The JTB definition came under severe criticism in the 20th century, mainly due to a series of counterexamples given by Edmund Gettier.

In other words, he made the correct choice (believing that the man who will get the job has ten coins in his pocket) for the wrong reasons.

Gettier then goes on to offer a second similar case, providing the means by which the specifics of his examples can be generalized into a broader problem for defining knowledge in terms of justified true belief.

[1][45] Some responses stay within the standard definition and try to make smaller modifications to mitigate the problems, for example, concerning how justification is defined.

[49][45] So while introducing an additional criterion may help exclude various known examples of cognitive luck, the resulting definition is often still susceptible to new cases.

[44][8][6] According to Keith Lehrer, cases of cognitive luck can be avoided by requiring that the justification does not depend on any false statement.

In this regard, Linda Zagzebski defines knowledge as "cognitive contact with reality arising out of acts of intellectual virtue".

Based on this line of thought, Ernest Sosa defines knowledge as a belief that "is true in a way manifesting, or attributable to, the believer's skill".

It therefore seems that while the observer does in fact have a true belief that her perceptual experience provides justification for holding, she does not actually know that there is a dog in the park.

[61] While it is indeed possible to bite the bullet and accept this conclusion, most philosophers find it implausible to suggest that we know nothing or almost nothing, and therefore reject the infallibilist response as collapsing into radical skepticism.

The British philosopher Simon Blackburn has criticized this formulation by suggesting that we do not want to accept as knowledge beliefs which, while they "track the truth" (as Nozick's account requires), are not held for appropriate reasons.

An account similar to Nozick's has also been offered by Fred Dretske, although his view focuses more on relevant alternatives that might have obtained if things had turned out differently.

"If, in some Gettier-like cases, I am wrong in my inference about the knowledge-hood of the given occurrent belief (for the evidence may be pseudo-evidence), then I am mistaken about the truth of my belief—and this is in accordance with Nyaya fallibilism: not all knowledge-claims can be sustained.

[69] A different approach characterizes knowledge in relation to the role it plays, for example, regarding the reasons it provides or constitutes for doing or thinking something.