Doctrine of mental reservation

Doctrine of mental reservation is like a game that grownups play. It is a way for people to be tricky and to not tell the whole truth. In this game, you can tell someone something that is true, but leave out part of the truth so it is not the whole story. For example, if you are asked where your friend is, you could say "I don't know," but you know that your friend is in the next room. That would be an example of mental reservation.