Rational is using your mind and doing the right thing in various situations. If a crippled person wants to live and you euthanize him against his will, that is not rational, because you are completely ignoring his will and because you are treating people like objects. Evolution as I said isn't entirely rational, because evolution is basically survival of the fittest. Evolution doesn't mainly listen to rationality, it firstly listens to the instict of surviving to make your generation go on as long as possible while the environment becomes tougher. Aa I said Hitler did not listen to anything other than his evil ways. No rationality in there.