Saint Augustine

Aurelius Augustinus (354–430 c.e.), or Saint Augustine, a saint and doctor of the Catholic Church, is the most important writer on lies in late antiquity, and one of the most important writers on lies of all time. He was the first thinker to systematically address the descriptive question of what is a lie, and the normative question of whether or not a lie is always impermissible. He was also the first thinker to address both of these questions in the light of Christian theology. He is one of the few thinkers (along with Saint Thomas Aquinas and Immanuel Kant) to hold that a lie is always impermissible.

Augustine discussed lying in many of his works, but he wrote two treatises devoted solely to the topic of lying: Lying (Mendacio; 395), and Against Lying (Contra Mendacium; 420).

It remains a matter of controversy as to what Augustine's final answer was to the first descriptive question of how a lie (mendacium) is to be defined, although much of his answer is clear. Augustine held that a lie requires “speech,” that is, “words or … some other kind of signifying act,” or more generally, the making of a statement. A statement is made in words or symbols—that is, conventional signs—that are spoken or written or otherwise expressed. For Augustine, it is not possible to lie by remaining silent. There can be no lie of omission in that sense. It is also not possible to lie by using nonlinguistic or natural signs. It is not possible to lie by smiling, or groaning, for example. Although one can deceive by these means, one cannot lie by these means, as there is no statement.

Augustine held that a lie requires that the statement that is made be contrary to what one believes to be true: “He lies who has one thing in his mind and says something else.” Augustine means by this that the liar (mendax) does not merely not believe his statement to be true but believes his statement to be false:

… the heart of the liar is said to be double, that is, twofold in its thinking: One part consisting in that knowledge he knows or thinks to be true yet does not so express; the other part consisting of that knowledge which he knows or thinks false yet expresses as true.

Someone who makes a statement that he neither believes to be true nor believes to be false is not lying. A lie therefore requires that the statement made be untruthful. If the person making the statement does not believe the statement to be false, then the person is not a liar, even if the statement that he makes happens to be false: “who utters falsehood does not lie if he believes or at least assumes that what he says is true.” To make a statement that one believes is false is an [Page 828]intentional act: “intention to tell a falsehood, i.e., what is, at least, believed to be false.” One cannot lie by mistake.

Augustine held that falsehood is not necessary for a lie and hence that a lie can be true or false: “that man is in conscience a liar who utters the truth thinking it to be false.” A person is judged to be lying or not lying on the basis of being untruthful: “he says what which he does not believe … even if what he does say be found to be true.”

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