Information about Moore's Paradox

G. E. Moore remarked once in a lecture on the absurdity involved in saying something like "It's raining outside but I don't believe that it is." This paradox, sometimes known as Moore's paradox, might well have been forgotten if not for the fact that Ludwig Wittgenstein is reported to have considered it to be Moore's most important contribution to philosophy.

Elaboration

There are two distinct versions of Moore's Paradox, the omissive and the commissive (terms popularized by Roy Sorensen^[1]) typically distinguished according to their syntactic form. In addition, many commentators hold that Moore's Paradox arises not only at the level of assertion but also at the level of belief. The omissive and the commissive are so-called due to the kind of epistemic (relating to knowledge) or doxastic (relating to opinion) errors a knower or rational believer would be guilty of with respect to the goals of maximizing truth and minimizing falsehood in their belief sets.

The omissive version concerns tokens of sentence-types of the following syntactic form: p and I do not believe that p (where p is any logically or semantically consistent proposition).

The commissive version concerns tokens of sentence-types of the following form: p and I believe that not-p.

The differences between these versions concern the place and consequent role of the negation sign.

Moore himself presented the paradox in two ways.^[2] The first more fundamental way of setting the problem up starts from the following three premises:

1. It can be true at a particular time both that p and that I do not believe that p (or that I believe that not-p)
2. I can assert or believe one of the two at a particular time.
3. I cannot without absurdity assert or believe both of them at the same time.

For example, it can be true right now both that it is raining and that I do not believe it (or that I believe that it is not raining). I can assert or believe that it is raining; I can assert or believe that I do not believe that it is raining (or, again, that I believe that it is not raining). But I cannot without absurdity assert or believe their conjunction. Why should this be so?

Moore presented the problem in a second way. The problem is compounded if we consider the following two facts. First, there is nothing absurd — i.e. nothing wrong — with the past-tense counterparts to Moore's sentences, e.g. Someone asserting or believing:

• It was raining and I did not believe that it was raining.

Second, there is nothing absurd with the second- or third-person counterparts to Moore's sentences. For example, someone asserting or believing that

• It is raining and he believes that it is not raining, or
• Elvis is dead and they do not believe that Elvis is dead.

Commentary

Most commentators take it as a condition on a satisfactory explanation of the peculiar absurdity involved in asserting or believing Moore's sentences that it explains the contradictory-like quality of using tokens of the omissive and commissive sentence-types. It is important to emphasize that what is absurd is not, prima facie, the sentence-type but using their tokens in the way that one does when one asserts or believes them.

An interesting point to make is that there do seem to be situations in which it arguably makes sense (i.e. is perfectly reasonable) to assert or believe Moore's sentences. For example, in the midst of a visual hallucination, one may see a pink elephant hurtling towards one at high speed though, fully aware that there are no pink elephants, not believe that it is so: thus "There is a pink elephant hurtling ... but I do not believe it." Such cases are constructible when the described case involves violations of normal conditions (e.g. brain damage, mental disorder, and Gettier cases (see Knowledge)).

While in more traditional philosophical circles, Moore's Paradox has perhaps been seen as a philosophical curiosity, Moore's sentences have been used by logicians, computer scientists, and those working in the artificial intelligence community, as examples of cases in which a knowledge, belief or information system is unsuccessful in updating its knowledge/belief/information store in the light of new or novel information. (For an introduction to some of these uses, see the various articles collected in a recent specialist journal).^[3] Philosophical interest in Moore's Paradox has recently undergone a resurgence, starting with Jaakko Hintikka,^[4] continuing with Roy Sorensen,^[1] David Rosenthal^[5] and the impending first publication of a collection of articles devoted to the problem.^[6]

Proposed Explanations

There have been several proposed constraints on a satisfactory explanation in the literature, including (though not limited to):

• It should explain the absurdity of both the omissive and the commissive versions.
• It should explain the absurdity of both asserting and believing Moore's sentences.
• It should preserve, and reveal the roots of, the intuition that contradiction (or something contradiction-like) is at the root of the absurdity.

The first two conditions have generally been the most challenged, while the third appears to be the least controversial. Some have claimed that there is no problem in believing the content of Moore's sentences, while others hold that an explanation of the problem at the level of belief will automatically provide us with an explanation of the absurdity at the level of assertion. Some have also denied that a satisfactory explanation to the problem need be uniform in explaining both the omissive AND commissive versions.

The most popular explanation to Moore's Paradox appeals to variations of the view that assertion implies or expresses belief in some way so that if someone asserts that p they imply or express the belief that p. On one of these views, if someone asserts p and conjoins it with the assertion (or denial) that he does not believe that p, then he has in that very act contradicted himself, for in effect what the speaker says is: I believe that p and I do not believe that p. Several versions of this expansive view ("expansive" since it replaces "p" with "I believe that p") exploit elements of speech act theory, distinguished according to the particular explanation given of the link between assertion and belief. Whatever version of this view is preferred, whether cast in terms of the Gricean intentions (see Paul Grice) or in terms of the structure of Searlean illocutionary acts (see speech act), it does not obviously apply to explaining the absurdity of the commissive version of Moore's Paradox.

An alternative minimalizing view (minimalizing because it replaces the "I believe that not-p" with "not-p") often controversially attributed to Wittgenstein, is that the assertion "I believe that p" often (though not always) functions as an alternative way of asserting "p", so that the semantic content of the assertion "I believe that p" is just p: it functions as a statement about the world and not about anyone's state of mind. Accordingly what someone asserts when they assert "p and I believe that not-p" is just "p and not-p" Asserting the commissive version of Moore's sentences is thus assimilated to the more familiar (putative) impropriety of asserting a contradiction (e.g. either asserting everything or asserting nothing, depending on one's views on the content of a contradiction).

Moore's Paradox forces us to think about such diverse topics as, among other things, the relation between assertion and belief, content and expression, the nature of belief, knowledge and rationality. There is, as yet however, no generally accepted explanation to Moore's Paradox in the literature.

Sources and notes

See also

• Faith and rationality
• Irrationality
• Wishful thinking
• Fideism
• Epistemology
• Hope
• Philosophical skepticism
• Mental illness

External links

• Standford Encyclopedia of Philosophy

•  • [ e] Fallacies of relevance
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