On moral relativists

“Suppose we think of a man made of water in an infinitely extended and bottomless ocean of water. 

Desiring to get out of water, he makes a ladder of water. 

He sets this ladder upon the water and against the water and then attempts to climb out of the water.

So hopeless and senseless a picture must be drawn of the natural man’s methodology based as it is upon the assumption that time or chance is ultimate. On his assumption his own rationality is a product of chance. On his assumption even the laws of logic which he employs are products of chance. The rationality and purpose that he may be searching for are still bound to be products of chance.”

— Cornelius Van Til, The Defense of the Faith (P&R, 1972), p. 102, writing on the inconsistencies present for moral relativists. What makes your ethical opinion hold water?