Lie: a dishonest or illicit falsehood. Lying is when we deliberately express ourselves in words and signs, in a false manner, with the aim of doing harm or damage. Yet the person we address has the right to know our thoughts. We are therefore obliged to provide him with the means of knowing them to the extent that we are able. It appears from this that we do not lie every time we speak in a way that is not in agreement with either things as they are or with our own thoughts. It follows therefore that the logical truth, which consists in simple conformity of our words and things as they are, does not always answer to the moral truth. It follows further that those who make no distinction between lying and uttering a falsehood are gravely mistaken. Lying is a dishonest act and deserves to be condemned. Nevertheless, we can utter a casual falsehood. We can utter one which is permissible, praiseworthy, and even necessary. Consequently, a falsehood that the circumstances render as such, must not be confounded with the lie , which reveals a weak soul or a vicious character.

We must not therefore call those people liars who use ingenious fictions or fables as a means of instruction or to protect the innocence of someone or to calm a violent person ready to do harm or to hide state secrets which involve the revelation of these secrets to the enemy. And so also in similar cases, these fictions and fables have for us or for others a usefulness that is legitimate and entirely innocent.

However, every time we have clear obligation faithfully to reveal our thoughts to another who has a right to know them, it would be criminal to suppress one part of the truth or to employ equivocations or mental reservations. This is why Cicero condemns the Roman who, after the battle of Cannes, having received from Hannibal permission to return to Rome on condition that he return to camp. Then, having left the camp, he returned under the pretext of having forgotten something, and believed through this stratagem to be free of his pledge.

Let us conclude that if the lie, the equivocation, and the mental reservation are odious, there are innocent falsehoods in discourse that prudence demands or authorizes. For as much as the word is the interpretation of the thought, it does not always follow that the word says everything we think. To the contrary, it is certain that the use of this faculty must be submitted to the light of the law of reason, to which belongs the right to decide which things it must and must not reveal. Finally, in order to be ready to declare naively what we have in our spirit, it is necessary that those to whom we are speaking have the right to know our thoughts.