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Theory of justification

Theory of justification is that part of epistemology that attempts to understand the justification of statements and beliefs.



Epistemologists are concerned with various epistemic features of belief, which include the ideas of justification, warrant, rationality, and probability. Of these four terms, the term that has been most widely used and discussed in the past twenty years is justification. Stephen Pepper (1942), in his "world hypothesis" theory of the history of epistemology, uses the term warrant. The theory of justification attempts to answer questions such as "What is justification?" or "When is a belief justified, and when not?"

Subjects of justification

Many things can be justified. Beliefs, actions, emotions, claims, laws, theories and so on. Epistemology focuses on beliefs. In part this is because of the influence of the Theaetetus account of knowledge as "justified true belief". More generally, the theory of justification focuses on the justification of statements or propositions.

Justification is a normative activity

One way of explaining the theory of justification is to say: A justified belief is one which we are within our rights in holding. By this is meant, not political rights, or moral rights, but "intellectual" rights.

In some way each of us is responsible for what we believe. We don't just go off and believe anything. We each have an intellectual responsibility or obligation, to believe what is true and to avoid believing what is false. Being intellectually responsible involves being within one's intellectual rights in believing something; in such cases one is justified in one's belief.

Thus, justification is a normative notion. That means that it has to do with norms, rights, responsibilities, obligations, and so forth. The standard definition is that a concept is normative iff it is a concept regarding or depending on the norms, or obligations and permissions (very broadly construed), involved in human conduct. It is generally accepted that the concept of justification is normative, because it is defined as a concept regarding the norms of belief.


If a belief is justified, there is something which justifies it. The thing which justifies a belief can be called its justifier. If a belief is justified, then it has at least one justifier. An example of a justifier would be some evidence that I accept. For example, if a woman is aware of the fact that her husband returned from a business trip smelling like perfume, and that his shirt has smudged lipstick on its collar, the perfume and the lipstick can be evidence for her belief that her husband is having an affair. In that case, the justifiers are all the perfume and the lipstick, or more specifically her acceptance of that evidence; the belief that is justified is her belief that her husband is having an affair.

Not all justifiers would have to be what can properly be called "evidence"; there might be some totally different kind of justifiers out there. But to be justified, a belief has to have a justifier.

But this raises an important question: What sort of thing can be a justifier?

Three things that have been suggested are:

  1. Beliefs only.
  2. Beliefs together with other conscious mental states.
  3. Beliefs, conscious mental states, and other facts about us and our environment (which we may not have access to).

At least sometimes, the justifier of a belief is another belief. When, to return to the earlier example, the woman believes that her husband is having an affair she bases that belief on other beliefs — namely, the lipstick and perfume. Strictly speaking, her belief isn't based on the evidence itself — after all, what if she did not believe it? What if she thought that all of that evidence were just a hoax? For that matter, what if the evidence existed, but she did not know about it? Then of course, her belief that her husband is having an affair wouldn't be based on that evidence, because she did not know it was there at all; or, if she thought the evidence were a hoax, then surely her belief couldn't be based on that evidence. When a belief is based on evidence, actually what my belief is based on is another belief, namely, a belief or beliefs about the evidence.

Consider a belief P. Either P is justified, or P is not justified. If P is justified, then another belief Q may be justified by P. If P is not justified, then P cannot be a justifier for any other belief: neither for Q, nor for Q's negation.

For example, suppose someone might believe that there is intelligent life on Mars, and base this belief on a further belief, that there is a feature on the surface of Mars that looks like a face, and that this face could only have been made by intelligent life. So the justifying belief is: That face-like feature on Mars could only have been made by intelligent life. And the justified belief is: There is intelligent life on Mars. But suppose further that the justifying belief is itself totally unjustified. One would in no way be in one's intellectual rights to suppose that this face-like feature on Mars could have only been made by intelligent life; that view would be totally irresponsible, intellectually speaking. Such a belief would be unjustified. It has a justifier, but the justifier is itself not justified. A belief can only be justified by some belief which is itself justified; notably with exception of the belief that one is capable, at least in principle, to distinguish a belief which is justified from one that's not.

If a belief, Q, is justified by another belief, P, then P must itself be justified.

See also: knowledge (philosophy)

Last updated: 08-10-2005 21:55:21
Last updated: 08-18-2005 06:00:23