I have never used mental reservation in explaining any teachings of the Church. Nor would I be justified in doing so. Even though mental reservation can be lawful in certain circumstances, you must not think that the Church allows it as a regular thing. It can be lawful, for although no one is ever allowed to say what is not true, one is not always obliged to say what is true. In mental restriction no lie is told, but part of the truth is withheld. Thus, to save a small boy from a bully, another lad could say, “He ran down this street towards the station.” But he does not add, “And he turned down the first street on the right.” He reserves that information within his own mind, and the mental restriction is quite lawful in such a case. However, since it misleads, the Church says that mental restriction is lawful only when there are sufficiently grave reasons either of j’ustice or of charity to justify it. ft is not /awfu/ whenever we please. But there is no sufficient reason for mental reservation when one is asked to explain the teachings of the Catholic Church, and in my replies I have never made use of it.
Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty