Moore's paradox
Encyclopedia
Moore's paradox concerns the putative absurdity involved in asserting a first-person present-tense sentence such as 'It's raining but I don't believe that it is raining' or 'It's raining but I believe that it is not raining'. The first author to note this apparent absurdity was G.E. Moore. These 'Moorean' sentences, as they have become known:
The 'paradox' consists in explaining why asserting a Moorean sentence is (or less strongly, strikes us as being) weird, absurd or nonsensical in some way. The term 'Moore's Paradox' is due to Ludwig Wittgenstein
, who considered it Moore's most important contribution to philosophy. Wittgenstein devoted numerous remarks to the problem in his later writings, which has brought Moore's Paradox the attention it might otherwise not have received. Subsequent commentators have further noted that there is an apparent residual absurdity in asserting a first-person future-tense sentence such as 'It will be raining and I will believe that it is not raining'.
Moore's Paradox has also been connected to many other of the well-known logical paradoxes including, though not limited to, the liar paradox
, the knower paradox, the unexpected hanging paradox
, and the Preface paradox
.
There is currently no generally accepted explanation of Moore's Paradox in the philosophical literature. However, while Moore's Paradox has perhaps been seen as a philosophical curiosity by philosophers themselves, Moorean-type sentences are 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.
(OM) P and NOT(I believe that P), or
(COM) P and I believe that NOT-P.
Commentators nowadays refer to these, respectively, as the omissive and commissive versions of Moore's Paradox, a distinction according to the scope of the negation in the apparent assertion of a lack of belief ('I don't believe that p') or belief that NOT-P. The terms pertain to the kind of doxastic error (i.e. error of belief) that one is subject to, or guilty of, if one is as the Moorean sentence says one is.
Moore himself presented the problem in two ways.
The first more fundamental way of setting the problem up starts from the following three premises:
I can assert that it is raining at a particular time. I can assert that I don't believe that it is raining at a particular time. If I say both at the same time, I am saying or doing something absurd. But the content of what I say—the proposition
the sentence expresses—is perfectly consistent: it may well be raining and I may not believe it. So why can't I assert that it is so?
Moore presents the problem in a second, distinct, way:
I can assert that I was a certain way (e.g. believing it was raining when it wasn't), that you, he, or they, are that way, but not that I am that way. Why not?
Many commentators—though by no means all—also hold that Moore's Paradox arises not only at the level of assertion
but also at the level of belief
. Interestingly imagining someone who believes an instance of a Moorean sentence is tantamount to considering an agent who is subject to, or engaging in, self-deception
(at least on one standard way of describing it).
, continuing with Roy Sorensen, David Rosenthal, Sydney Shoemaker
and the first publication, in 2007, of a collection of articles devoted to the problem.
There have been several proposed constraints on a satisfactory explanation in the literature, including (though not limited to):
The first two conditions have generally been the most challenged, while the third appears to be the least controversial. Some philosophers have claimed that there is, in fact, no problem in believing the content of Moore's sentences (e.g. David Rosenthal). Others (e.g. Sydney Shoemaker) 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 via the linking principle that what can reasonably be asserted is determined by what can reasonably be believed. Some have also denied (e.g. Rosenthal) that a satisfactory explanation to the problem need be uniform in explaining both the omissive AND commissive versions. Most of the explanations offered of Moore's paradox are united in holding that contradiction
is at the heart of the absurdity.
One type of explanation at the level of assertion exploits 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. Several versions of this view exploit elements of speech act
theory, which can be 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. To take one version of this type of explanation, 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. The absurdity of asserting p & I do not believe that p is thus revealed as being of a more familiar kind. Depending on one's view of the nature of contradiction, one might thus interpret a speaker of the omissive Moorean sentence as asserting everything (that is, asserting too much) or asserting nothing (that is, not asserting enough).
An alternative view 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 again assimilated to the more familiar (putative) impropriety of asserting a contradiction
.
At the level of belief, there are two main kinds of explanation. The first, much more popular one, agrees with those at the level of assertion that contradiction is at the heart of the absurdity. The contradiction is revealed in various ways, some using the resources of doxastic logic (e.g. Hintikka), others (e.g. Sorensen) principles of rational belief maintenance and formation, while still others appeal to our putative capacity for self-knowledge and the first-person authority (e.g. Shoemaker) we have over our states of mind.
Another alternative view, due to Richard Moran
, views the existence of Moore's paradox as symptomatic of creatures who are capable of self-knowledge, capable of thinking for themselves from a deliberative point of view, as well as about themselves from a theoretical point of view. On this view, anyone who asserted or believed one of Moore's sentences would be subject to a loss of self-knowledge—in particular, would be one who, with respect to a particular 'object', broadly construed, e.g. person, apple, the way of the world, would be in a situation which violates, what Moran calls, the Transparency Condition: if I want to know what I think about X, then I consider/think about nothing but X itself. Moran's view seems to be that what makes Moore's paradox so distinctive is not some contradictory-like phenomenon (or at least not in the sense that most commentators on the problem have construed it), whether it be located at the level of belief or that of assertion. Rather, that the very possibility of Moore's paradox is a consequence of our status as agents (albeit finite and resource-limited ones) who are capable of knowing (and changing) their own minds.
- can be true,
- are (logically) consistent, and moreover
- are not (obviously) contradictionContradictionIn classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical, usually opposite inversions of each other...
s.
The 'paradox' consists in explaining why asserting a Moorean sentence is (or less strongly, strikes us as being) weird, absurd or nonsensical in some way. The term 'Moore's Paradox' is due to Ludwig Wittgenstein
Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He was professor in philosophy at the University of Cambridge from 1939 until 1947...
, who considered it Moore's most important contribution to philosophy. Wittgenstein devoted numerous remarks to the problem in his later writings, which has brought Moore's Paradox the attention it might otherwise not have received. Subsequent commentators have further noted that there is an apparent residual absurdity in asserting a first-person future-tense sentence such as 'It will be raining and I will believe that it is not raining'.
Moore's Paradox has also been connected to many other of the well-known logical paradoxes including, though not limited to, the liar paradox
Liar paradox
In philosophy and logic, the liar paradox or liar's paradox , is the statement "this sentence is false"...
, the knower paradox, the unexpected hanging paradox
Unexpected hanging paradox
The unexpected hanging paradox, hangman paradox, unexpected exam paradox, surprise test paradox or prediction paradox is a paradox about a person's expectations about the timing of a future event The unexpected hanging paradox, hangman paradox, unexpected exam paradox, surprise test paradox or...
, and the Preface paradox
Preface paradox
The preface paradox, or the paradox of the preface, was introduced by David Makinson in 1965. Similar to the lottery paradox, it presents an argument according to which it can be rational to accept mutually incompatible beliefs...
.
There is currently no generally accepted explanation of Moore's Paradox in the philosophical literature. However, while Moore's Paradox has perhaps been seen as a philosophical curiosity by philosophers themselves, Moorean-type sentences are used by logicians, computer scientists, and those working in the artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...
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.
The problem
Since Jaakko Hintikka's seminal treatment of the problem, it has become standard to present Moore's Paradox as explaining why it is absurd to assert sentences that have the logical form:(OM) P and NOT(I believe that P), or
(COM) P and I believe that NOT-P.
Commentators nowadays refer to these, respectively, as the omissive and commissive versions of Moore's Paradox, a distinction according to the scope of the negation in the apparent assertion of a lack of belief ('I don't believe that p') or belief that NOT-P. The terms pertain to the kind of doxastic error (i.e. error of belief) that one is subject to, or guilty of, if one is as the Moorean sentence says one is.
Moore himself presented the problem in two ways.
The first more fundamental way of setting the problem up starts from the following three premises:
- It can be true at a particular time both that P, and that I do not believe that P.
- I can assert or believe one of the two at a particular time.
- It is absurd to assert or believe both of them at the same time.
I can assert that it is raining at a particular time. I can assert that I don't believe that it is raining at a particular time. If I say both at the same time, I am saying or doing something absurd. But the content of what I say—the proposition
Proposition
In logic and philosophy, the term proposition refers to either the "content" or "meaning" of a meaningful declarative sentence or the pattern of symbols, marks, or sounds that make up a meaningful declarative sentence...
the sentence expresses—is perfectly consistent: it may well be raining and I may not believe it. So why can't I assert that it is so?
Moore presents the problem in a second, distinct, way:
- It is not absurd to assert the past-tense counterpart, e.g. 'It was raining but I did not believe that it was raining'.
- It is not absurd to assert the second- or third-person counterparts to Moore's sentences, e.g. 'It is raining but you do not believe that it is raining', or 'Michael is dead but they do not believe that he is'.
- It is absurd to assert the present-tense 'It is raining and I don't believe that it is raining'.
I can assert that I was a certain way (e.g. believing it was raining when it wasn't), that you, he, or they, are that way, but not that I am that way. Why not?
Many commentators—though by no means all—also hold that Moore's Paradox arises not only at the level of assertion
Assertion
The term assertion has several meanings:* Assertion , a computer programming technique* Logical assertion, logical assertion of a statement* Proof by assertion, an assertion as opposed to an argument...
but also at the level of belief
Belief
Belief is the psychological state in which an individual holds a proposition or premise to be true.-Belief, knowledge and epistemology:The terms belief and knowledge are used differently in philosophy....
. Interestingly imagining someone who believes an instance of a Moorean sentence is tantamount to considering an agent who is subject to, or engaging in, self-deception
Self-deception
Self-deception is a process of denying or rationalizing away the relevance, significance, or importance of opposing evidence and logical argument...
(at least on one standard way of describing it).
Proposed explanations
Philosophical interest in Moore's paradox, since Moore and Wittgenstein, has undergone a resurgence, starting with, though not limited to, Jaakko HintikkaJaakko Hintikka
Kaarlo Jaakko Juhani Hintikka is a Finnish philosopher and logician.Hintikka was born in Vantaa. After teaching for a number of years at Florida State University, Stanford, University of Helsinki, and the Academy of Finland, he is currently Professor of Philosophy at Boston University...
, continuing with Roy Sorensen, David Rosenthal, Sydney Shoemaker
Sydney Shoemaker
Sydney Shoemaker is an American philosopher. Until his retirement, he was a Susan Linn Sage Professor of Philosophy at Cornell University. He holds a PhD from Cornell and BA from Reed. In 1971, he delivered the John Locke Lectures at Oxford University...
and the first publication, in 2007, of a collection of articles devoted to the problem.
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 philosophers have claimed that there is, in fact, no problem in believing the content of Moore's sentences (e.g. David Rosenthal). Others (e.g. Sydney Shoemaker) 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 via the linking principle that what can reasonably be asserted is determined by what can reasonably be believed. Some have also denied (e.g. Rosenthal) that a satisfactory explanation to the problem need be uniform in explaining both the omissive AND commissive versions. Most of the explanations offered of Moore's paradox are united in holding that contradiction
Contradiction
In classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical, usually opposite inversions of each other...
is at the heart of the absurdity.
One type of explanation at the level of assertion exploits the view that assertion implies or expresses belief
Belief
Belief is the psychological state in which an individual holds a proposition or premise to be true.-Belief, knowledge and epistemology:The terms belief and knowledge are used differently in philosophy....
in some way so that if someone asserts that p they imply or express the belief that p. Several versions of this view exploit elements of speech act
Speech act
Speech Act is a technical term in linguistics and the philosophy of language. The contemporary use of the term goes back to John L. Austin's doctrine of locutionary, illocutionary, and perlocutionary acts...
theory, which can be 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
Paul Grice
Herbert Paul Grice , usually publishing under the name H. P. Grice, H...
) or in terms of the structure of Searlean illocutionary acts (see speech act
Speech act
Speech Act is a technical term in linguistics and the philosophy of language. The contemporary use of the term goes back to John L. Austin's doctrine of locutionary, illocutionary, and perlocutionary acts...
), it does not obviously apply to explaining the absurdity of the commissive version of Moore's paradox. To take one version of this type of explanation, 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. The absurdity of asserting p & I do not believe that p is thus revealed as being of a more familiar kind. Depending on one's view of the nature of contradiction, one might thus interpret a speaker of the omissive Moorean sentence as asserting everything (that is, asserting too much) or asserting nothing (that is, not asserting enough).
An alternative view 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 again assimilated to the more familiar (putative) impropriety of asserting a contradiction
Contradiction
In classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical, usually opposite inversions of each other...
.
At the level of belief, there are two main kinds of explanation. The first, much more popular one, agrees with those at the level of assertion that contradiction is at the heart of the absurdity. The contradiction is revealed in various ways, some using the resources of doxastic logic (e.g. Hintikka), others (e.g. Sorensen) principles of rational belief maintenance and formation, while still others appeal to our putative capacity for self-knowledge and the first-person authority (e.g. Shoemaker) we have over our states of mind.
Another alternative view, due to Richard Moran
Richard Moran
Richard A. Moran is a San Francisco based business leader, venture capitalist, social scientist, best selling author and evangelist for organization effectiveness...
, views the existence of Moore's paradox as symptomatic of creatures who are capable of self-knowledge, capable of thinking for themselves from a deliberative point of view, as well as about themselves from a theoretical point of view. On this view, anyone who asserted or believed one of Moore's sentences would be subject to a loss of self-knowledge—in particular, would be one who, with respect to a particular 'object', broadly construed, e.g. person, apple, the way of the world, would be in a situation which violates, what Moran calls, the Transparency Condition: if I want to know what I think about X, then I consider/think about nothing but X itself. Moran's view seems to be that what makes Moore's paradox so distinctive is not some contradictory-like phenomenon (or at least not in the sense that most commentators on the problem have construed it), whether it be located at the level of belief or that of assertion. Rather, that the very possibility of Moore's paradox is a consequence of our status as agents (albeit finite and resource-limited ones) who are capable of knowing (and changing) their own minds.
See also
- BeliefBeliefBelief is the psychological state in which an individual holds a proposition or premise to be true.-Belief, knowledge and epistemology:The terms belief and knowledge are used differently in philosophy....
- ConsistencyConsistencyConsistency can refer to:* Consistency , the psychological need to be consistent with prior acts and statements* "Consistency", an 1887 speech by Mark Twain...
- Inconsistency
- Epistemology
- ContradictionContradictionIn classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical, usually opposite inversions of each other...
- IrrationalityIrrationalityIrrationality is cognition, thinking, talking or acting without inclusion of rationality. It is more specifically described as an action or opinion given through inadequate reasoning, emotional distress, or cognitive deficiency...
- List of paradoxes
- RationalityRationalityIn philosophy, rationality is the exercise of reason. It is the manner in which people derive conclusions when considering things deliberately. It also refers to the conformity of one's beliefs with one's reasons for belief, or with one's actions with one's reasons for action...
- Self-knowledge (psychology)
- Self-deceptionSelf-deceptionSelf-deception is a process of denying or rationalizing away the relevance, significance, or importance of opposing evidence and logical argument...
- Philosophy of MindPhilosophy of mindPhilosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...
- DoublethinkDoublethinkDoublethink, a word coined by George Orwell in the novel 1984, describes the act of simultaneously accepting two mutually contradictory beliefs as correct, often in distinct social contexts. It is related to, but distinct from, hypocrisy and neutrality. Its opposite is cognitive dissonance, where...