The modern mind has two lines of defense...The second claims that to tie ourselves to an immutable moral code is to cut off all progress and acquiesce in 'stagnation'...Let us strip it of legitimate emotional power it derives from the word 'stagnation' with its suggestion of puddles and mantled pools. If water stands too long it stinks. To infer thence that whatever stands long must be unwholesome is to be the victim of metaphor. Space does not stink because it has preserved its three dimensions from the beginning. The square on the hypotenuse has not gone [moldy] by continuing to equal the sum of the squares on the other two sides. Love is not dishonored by constancy...For the emotive term 'stagnant' let us substitute the descriptive term 'permanent'. Does a permanent moral standard preclude progress? On the contrary except on the supposition of a changeless standard, progress is impossible. If good is a fixed point, it is at least possible that we should get nearer and nearer to it; but if the [terminal] is as mobile as the train, how can the train progress toward it? Our ideas of the good may change, but they cannot change either for the better or the worse if there is no absolute and immutable good to which they can approximate or from which they can recede. We can go on getting a sum ore and more nearly right only if the one perfectly right answer is 'stagnant.'
CS Lewis
The Poison of Subjectivism
