“The Poison of Subjectivism” is a very complicated essay. Lewis’s first points are that it is impossible to be against subjectivism without being subjective in the process. If a person says that there is no good and evil he is already being subjective. Likewise Lewis says that a “scientist has to assume the validity of his own logic.” Lewis contends that the present “value judgments” which are the basis of the Moral Law and traditional explanations of good and bad cannot be removed from man’s reasoning.
His first reason is that “the human mind has no more power of inventing a new value than of planting a new sun in the sky.” The second reason is that “every attempt to do so consists in arbitrarily selecting some one maxim of traditional morality, isolating it from the rest, and erecting it into an unum necessarium.”
Lewis then examines two arguments against traditional morals. First all traditional morals have the same foundational elements. Lewis shows this in a similar way to how he portrayed that the Natural Law is found in all cultures in “Mere Christianity.” Basically while slight deviations are present all cultures maintain favorable views of such actions as honesty, and alms giving and negative views of such actions as oppression, murder etc. A second complaint against traditional morals is that in referring to them we are prohibiting progress. As Lewis shows, trying to overtake a goal that is constantly moving is impossible. Furthermore, if we desire to progress in our morality we must first have something to build upon. The traditional morals are a good foundation for the progress of man.
Lewis goes on to reference “common grace” by showing how even if the core of humans are unrighteous we can still perceive good and bad. (Common grace contends that by God’s grace humans maintain some goodness despite their overwhelmingly bad nature resulting from the fall)
Finally Lewis asserts that God is goodness. If goodness was merely what God commands us to do then evil would have an equal claim upon us, and this is not so. If God chose his commands based on what is good then there would be a law greater than God and there cannot be anything greater than God. Lewis compares this confusing relationship between God and goodness to the relationship of the Trinity in which Three (Father, Son, and Holy Spirit) are one and yet Three are distinct. Our human minds have difficulty understanding these relationships because we can only comprehend the existence of three dimensions. It follows from this reading that man cannot remove himself from subjectivism to the traditional law of morality or value judgment; because God is good neither can man remove himself from knowledge of God.