The Reality of the Law (Mere Christianity 3/33)
Although noone can argue that we were supposed to be Perfect because we were made so in the Garden of Eden, im not sure when you have done your best to rule out GOD as a means by which to get to a moral absolute being in existance, that its somehow alright to make the assumption that we are supposed to be perfect, and thats why we know what perfect could be, and that would be realized if we followed the law of nature.
Although his argument from that point on is fine, it could have been shortened by the words of "Awareness" and "Consciousness" as to how come humans are in possession of the knowledge of this law and other life is not.
Lewis uses the argument that people follow this rule because they realize without order there is chaos, I would have used the argument that actually people follow rules of society out of fear of punishment if they break them. I think thats a stronger reason in this day and age, but he was writing during the second world war, so that may account for that.
Other then that I can accept this chapter in its entireity. Like I mentioned I dont really take issue with his conclusion, I take issue with the arguments that got him there, because I think there are better ones to be made.