SORITES ISSN 1135-1349
Issue #17 -- October 2006. Pp. 27-30
The Logic of Lying
Copyright © by Moses Òkè and SORITES
The Logic of Lying
Moses Òkè


Usually, people normally expect that others should take whatever claims they make as true. Also, whenever it is said that a claim is a lie, most people generally tend to presume that the claim is false. It is also generally believed that a truthfully made statement is true.

In this discussion, I wish to call due attention to the nature of a lie to show that it is not the case that a lie is necessarily a false statement, just as a truthfully made statement is not necessarily a true statement.

The statements or claims we make are expressions of our beliefs and thoughts; our statements are reports of the information at our disposal. The information could have come to us from any sources whatsoever. The epistemic or any other value that we place on each source and kind of information is a different matter altogether, and not the concern of the present discussion.

The context for this discussion can be conveniently set in Chisholm's treatment of «the Epimenides». Accordingly to Chisholm (1977:91),

If a man says, `I am now lying' is he saying something that is true or something that is false? Either possibility seems to lead to a contradiction... we bring the problem into sharper focus if we consider a man who says more baldly, `What I am saying is false'.

By definition, a lie is a dishonestly made statement. It is a statement which deviates from what its author actually knows, believes or holds to be true. To lie is, therefore, to say is false what one believes is true, or to say is true what one believes is false. We may say that a lie is an intentional and deliberate distortion by someone of what he or she believes or takes to be true. It is a wilful misrepresentation, in one's statement, of one's beliefs. In this regard, it is important to note that the opposite concept of lying is not truth, but truthfulness. It should also be noted that whereas truth and falsity are epistemic terms, truthfulness and lying (i.e. untruthfulness) are moral concepts. It is in this context that we can see how a truthfully made statement might be untrue, while an untruthfully made statement (i.e. lie) might not be untrue.

The truthful person is one who honestly says what he or she believes or thinks as he or she believes or thinks it to be. There is agreement between a belief and its corresponding expression, by a truthful person. However, a person's belief that P is true, or that P is false, does not imply that P is true, or that P is false. Wittgenstein indicates this point clearly when he says:

From its seeming to me -- or to anyone -- to be so, it doesn't follow that it is so... For it is not as though the proposition `It is so' could be inferred from someone else's utterance: `I know it is so'. Nor from the utterance together with its not being a lie (Wittgenstein 1974:2, 3).

The truth-value of a statement is therefore independent of the manner of its utterance as well as the moral status of its author. An honest person and a dishonest person could equally say what is true, as well as what is false, on the same issue.

Statements, being the expression of their author's beliefs, thoughts, ideas, feelings, etc., could, for one reason or the other, be wrong or inaccurate with reference to what they seek to express. A person might in his statement express his belief, etc. incorrectly owing to ignorance, mistake, or illness. In each of these cases, the error involved is epistemic, without any intention to deceive or misinform anyone. On the other hand, when a statement is not an accurate expression of its author's belief owing to his or her intention to do mischief, deliberately to misinform and deceive those to whom the statement is communicated, we have a case of dishonesty that falls within the purview of morality rather than that of epistemology.

Hallen (1998:187-204, and 2000:13-35) hints at the tendency of people to mistake truthfulness for truth when they evaluate one another's statements. For instance, people generally tend not to believe or hold as true whatever a person known to be a liar says. On the other hand, people generally feel inclined to accept as true whatever anyone adjudged to be truthful or honest says. Wiredu (1996:106) also remarks how the connection between truthfulness and truth makes the word `truth' ambiguous and confusing.

However, people generally expect that other persons would accept their claims as true. Thus, even the person who says `What I am saying is false', or the one who says `I am lying' would want and expect to be taken as saying the truth. The point to note here is that the person who declares his or her own statement false might, in his or her declaration, be making a false statement, such that the allegedly false statement may in fact be true. On the other hand, the self-acclaimed liar might be saying the truth about himself or herself, but the statement might also be true. That is, a liar's lie might be a true statement. This points to the fact that a liar does not necessarily say what is false whenever he lies.

A lie might be a true statement if the belief which the liar held to be true, and which he or she sought to distort, was in fact false. This follows from the fact that owing to a number of epistemic defects, a person may sincerely hold a false belief to be true, or a true belief to be false, and say honestly that it is true, or that it is false, respectively. From this, it is to be noted that a person's truthfulness does not imply the truth of his or her statements. A truthful person is not a person who is filled with truths and nothing but truths. In the same vein, a person's untruthfulness (or habit of lying) does not imply the falsity of his or her statements. An untruthful person (a liar) is not a person full of nothing but untruths. In other words, a truthfully made statement could be either true or false, just as a lie, too, could be either true or false independently of the motive or character of its author.

Whether a statement is true or false is, therefore, not a function of the moral character of the statement's author, but rather of the situation to which the statement pertains. Hence, we may have (i) statements that are truthfully made but which are false, (ii) statements that are truthfully made and are true, and (iii) lies that are true statements. We may thus say very rightly that truthfulness and lying are to persons as truth and falsity are to statements. The ability to lie is thus an essential characteristic of persons, just as falsity-possibility is an essential feature of statements, thoughts and beliefs.

Both a truthful person and a liar could hold false beliefs. However, whereas the truthful person expresses and communicates his or her belief without any deliberate or intentional distortion, the liar deliberately and intentionally communicates the opposite, the negation, the caricature or the counterfeit of his or her belief. It has to be re-emphasised, however, that a truthfully made statement is not necessarily a true statement, or a statement of truth. This is so in the same way that Hanson (1952:4-24) has shown that a factual statement is not necessarily a statement of fact. In a related reference, Wittgenstein (1953: Part II, 192e) cautions that we should not mistake a hesitant assertion for an assertion of hesitancy. Similarly, we should not uncritically regard an untruthfully made statement as an untrue statement, or a truthfully made statement as a true statement.

The liar might hold as true a belief that is false. That is, a person who lies about his or her belief could have unintentionally said the truth. This comes to saying that the lie (i.e. the negation or distortion of the belief held to be true) was false. On the other hand, a lie could, unintended though, be true if the author of the lie originally held as false a true belief. Either way, there is no contradiction involved in the statement or the assertion of it. What we have is a disagreement between a person's belief and his or her statement that purports to express that belief. Hence, whenever a lie is true, the logical implication is that the liar was mistaken about the truth-value of the belief that he or she sought to misrepresent or distortedly communicate. In the case of a truthful person, his or her statement will be false only when his belief is false and true whenever his belief is true.

It is important to note that in the case of a liar, his or her lie could be false both when the corresponding belief is true and when it is false. This is because the lie may sometimes not be a logical negation of the liar's belief; it could be a different false statement that neither truly expresses the liar's mistaken false belief, nor falsely expresses his or her true belief.

We can illustrate the possibilities with a simple example. Let us assume that today is Monday. A liar (or any other person, for that matter) could believe that today is Monday or that today is any other day of the week, Friday for example. That is, the liar's belief could be either true or false. If a liar believes falsely that today is Friday, but untruthfully says that today is Tuesday, for instance, the lie would be a false statement. Also, if the liar believes truly that today is Monday but, lying, says that today is Tuesday, for instance, the lie would also be a false statement. The only instance, therefore, when a lie is necessarily false is when the liar's corresponding belief that was distorted was true. In other instances, the lie could be either true or false.

We conclude, therefore, that a lie is not necessarily a false statement. This shows, as Wittgenstein (1953:182) had noted, that the logical relations between the words `lie', `true', and `false' are «more involved... than we are tempted to think.»


Moses Òkè
Department of Philosophy
Obafemi Awolowo University
Ile-Ife, Nigeria
<rosenhillme [at]>

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