It is in ethics that “progressivism” is most deadly. Astonishingly, few modern minds see the simple and obvious point that an unchanging standard, far from being the enemy of moral progress, is the necessary condition for it: “Does a permanent moral standard preclude progress? On the contrary, except on the supposition of a changeless standard, … progress is impossible…if the terminus is as mobile as the train, how can the train progress toward it?”
— Peter Kreeft, C.S. Lewis for the Third Millennium, pg. 16