When the only thing that determines what is morally right is one’s individual, subjective judgment, then there is no overarching moral truth to which all are bound. In such a situation, those who have the greatest power can impose their positions on other, unchecked by any authority apart from themselves. Indeed, such an understanding of the infallibility of a subjective conscience would free from guilt, for example, even those who had committed unspeakable atrocities….
—from the Foreword by John M. Haas of The National Catholic Bioethics Center
What characterizes man as man is not that he asks about the “can” but about the “should,” and that he opens himself to the voice and demands of truth.
It seems to me that this was the final meaning of the Socratic search, and it is the profoundest element in the witness of all martyrs. They attest to the fact that man’s capacity for truth is a limit on all power and a guarantee of man’s likeness to God. It is precisely in this way that the martyrs are the great witnesses of conscience, of that capability given to man to perceive the “should” beyond the “can” and thereby render possible real progress, real ascent.
—from On Conscience, a collection of two essays by Joseph Cardinal Ratzinger (Pope Benedict XVII) – from the first essay Conscience and Truth which was the keynote address of the Tenth Bishops’ Workshop of the National Catholic Bioethics Center, on “Catholic Conscience: Foundation and Formation,” February 1991