The difficulty of conceptualizing the perfect definition has caused many over the centuries to insist on the existence of the necessary lie. Such a lie arises from a conflict between justice and veracity when the exercise of both virtues is demanded by the selfsame moral situation. In other words, we are obliged to tell the truth, and we are also obliged to keep secrets, but there are times when the only way to keep a secret is to lie. Both keeping secrets and speaking truthfully are included under all standard expositions of the natural law and the eighth commandment. When our obligation to protect a secret conflicts with our obligation to tell the truth, the result is a necessary lie—necessary not because it helps us to avoid some potential pain but because it is the only way to preserve justice. On this reading, a very particular exception to the rule exists when there are conflicting moral requirements. We may—indeed, we must—deceive the thugs because it is the lesser of two evils.
