However, when I mentioned before about Hitler & stalin, they were actually trying to implement social darwinism, and those who supported them wanted to live in a 'facist state'. They thought evolution justified it, and would be a good thing. So the question is, how can one evolutionist who believes what Hitler did, be called morally wrong by another evolutionist who believes otherwise? What is there in Darwinian evolution, that can determine whose morality is right?
Well, given that Hitler was a creationist and Stalin was a Lysenkoist, a Darwiniist could start by pointing out that they were both wrong about biology.