Plato in The Republic reports a discussion between Socrates and Cephalus. Is justice to always tell the truth? Is justice to give back to everyone what one has received?
Plato shows that no, justice is not to always tell the truth, nor to always return what one has received.
(331 c) But this very virtue, justice, shall we simply say that it consists in telling the truth and giving back what one has received from someone, or that acting in this way is sometimes just, sometimes unjust? I explain it this way: everyone agrees that if one receives weapons from a sane friend who, having gone mad, asks for them back, one should not give them back to him, and that the one who would give them back would not be just, nor would the one who would want to tell the whole truth to a man in this state.
(331 d) That is right, he says.
Therefore, this definition is not the definition of justice: telling the truth and returning what one has received.”
