Do not think of knocking out another person's brains because he differs in opinion from you. It would be as rational to knock yourself on the head because you differ from yourself ten years ago.
Any intelligent person knows that life is a beautiful thing and that the purpose of life is to be happy, said my father as he watched the three beauties. But it seems only idiots are ever happy. How can we explain this?
We have become, by the power of a glorious evolutionary accident called intelligence, the stewards of life's continuity on earth. We did not ask for this role, but we cannot abjure it. We may not be suited to it, but here we are.