Epistemology

Epistemology, from the Greek words episteme (knowledge) and logos (word/speech) is the branch of philosophy that deals with the nature, origin and scope of knowledge. It has historically been one of the most investigated and most debated of all philosophical discourses.

Definition of knowledge

Distinguishing knowing that from knowing how

Suppose that Fred says to you: "The fastest swimming stroke is the front crawl. One performs the front crawl by oscillating the legs at the hip, and moving the arms in an approximately circular motion". Here, Fred has propositional knowledge of swimming and how to perform the front crawl.

Related Topics:
Fred - Swimming - Front crawl - Propositional knowledge

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However, if Fred acquired this propositional knowledge from an encyclopedia, he will not have acquired the skill of swimming: he has some propositional knowledge, but does not have any procedural knowledge or "know-how". In general, one can demonstrate know-how by performing the task in question, but it is harder to demonstrate propositional knowledge. Michael Polanyi popularised the term tacit knowledge to distinguish the ability to do something from the ability to describe how to do something. Gilbert Ryle had previously made a similar point in discussing the characteristics of intelligence. His ideas are summed up in the aphorism "efficient practice precedes the theory of it". Someone with the ability to perform the appropriate moves is said to be able to swim, even if that person cannot precisely identify what it is they do in order to swim. This distinction is often traced back to Plato, who used the term techne or skill for knowledge how, and the term episteme for a more robust kind of knowledge in which claims can be true or false.

Related Topics:
Encyclopedia - Skill - Procedural knowledge - Michael Polanyi - Tacit knowledge - Gilbert Ryle - Intelligence - Aphorism - Plato - Techne - Episteme

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Knowledge and belief

There are two slightly different meanings of belief that must be distinguished. In the first sense John might "believe in" his cousin Joe. This may mean that he is willing to loan Joe money, trusting in his paying it back. In this sense, John might say, "I know it is safer to fly than drive, yet I don't believe it" in which case John doesn't trust in the pilots of commercial aircraft, even though as a cognitive matter he may understand the pertinent statistics.

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In the second sense of belief, to believe something just means to think that it is true. That is, to believe P is to do no more than to think, for whatever reason, that P is the case. It is this sort of belief that philosophers most often mean when they are discussing knowledge. The reason is that in order to know something, one must think that it is true - one must believe (in the second sense) it to be the case.

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Consider someone saying "I know that P, but I don't think P is true". The person making this utterance has, in a profound sense, contradicted themselves. If one knows that P, then, amongst other things, one thinks that P is indeed true. If one thinks that P is true, then one believes P. (See: Moore's paradox.)

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Knowledge is distinct from belief and opinion. If someone claims to believe something, they are claiming that they think that it is the truth. But of course, it might turn out that they were mistaken, and that what they thought was true was actually false. This is not the case with knowledge. For example, suppose that Jeff thinks that a particular bridge is safe, and attempts to cross it; unfortunately the bridge collapses under his weight. We might say that Jeff believed that the bridge was safe, but that his belief was mistaken. We would not say that he knew that the bridge was safe, because plainly it was not. For something to count as knowledge, it must be true.

Related Topics:
Belief - Opinion - Truth

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Similarly, two people can believe things that are mutually contradictory, but they cannot know (unequivocal) things that are mutually contradictory. For example, Jeff can believe the bridge safe, while Jenny believes it unsafe. But Jeff cannot know the bridge is safe and Jenny know that the bridge is unsafe. Two people cannot know contradictory things.

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Justified true belief

The Theaetetus account of Plato further develops the definition of knowledge. We know that, for something to count as knowledge, it must be true, and be believed to be true. Plato argues that this is insufficient, and that in addition one must have a reason or justification for that belief.

Related Topics:
Theaetetus - Plato

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Plato defined knowledge as justified true belief.

Related Topics:
Justified - True - Belief

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One implication of this definition is that one cannot be said to "know" something just because one believes it and that belief subsequently turns out to be true. An ill person with no medical training but a generally optimistic attitude might believe that she will recover from her illness quickly, but even if this belief turned out to be true, on the Theaetetus account the patient did not know that she would get well, because her belief lacked justification.

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Knowledge, therefore, is distinguished from true belief by its justification, and much of epistemology is concerned with how true beliefs might be properly justified. This is sometimes referred to as the theory of justification.

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The Theaetetus definition agrees with the common sense notion that we can believe things without knowing them. Whilst knowing p entails that p is true, believing in p does not, since we can have false beliefs. It also implies that we believe everything that we know. That is, the things we know form a subset of the things we believe.

Related Topics:
Entails - Subset

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The problem of defining knowledge

For most of philosophical history, "knowledge" was taken to mean belief that was justified as true to an absolute certainty. Any less justified beliefs were called mere "probable opinion." This viewpoint still prevailed at least as late as Bertrand Russell's early 20th century book The Problems of Philosophy. In the decades that followed, however, the notion that the belief had to be justified to a certainty lost favour.

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In the 1960s, Edmund Gettier criticised the Theaetetus definition of knowledge by pointing out situations in which a believer has a true belief justified to a reasonable degree, but not to a certainty, and yet in the situations in question, everyone would agree that the believer does not have knowledge.

Related Topics:
1960s - Edmund Gettier

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A priori versus a posteriori knowledge

Western philosophers for centuries have distinguished between two kinds of knowledge: a priori and a posteriori knowledge.

Related Topics:
Philosophers - A priori - A posteriori

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A priori knowledge is knowledge gained or justified by reason alone, without the direct or indirect influence of any particular experience (here, experience usually means observation of the world through sense perception. See Rationalism, below, for clarification.)

Related Topics:
Reason - Rationalism

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A posteriori knowledge is any other sort of knowledge; that is, knowledge the attainment or justification of which requires reference to experience. This is also called empirical knowledge.

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One of the fundamental questions in epistemology is whether there is any non-trivial a priori knowledge. Generally speaking rationalists believe that there is, while empiricists believe that all knowledge is ultimately derived from some kind of external experience.

Related Topics:
Epistemology - Rationalists - Empiricists

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The fields of knowledge most often suggested as having a priori status are logic and mathematics, which deal primarily with abstract, formal objects.

Related Topics:
Logic - Mathematics

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Empiricists have traditionally denied that even these fields could be a priori knowledge. Two common arguments are that these sorts of knowledge can only be derived from experience (as John Stuart Mill argued), and that they do not constitute "real" knowledge (as David Hume argued).

Related Topics:
John Stuart Mill - David Hume

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