Social darwinism is a romanticisation of nature. It proclaims that "survival of the fittest" should be a moral motto for how we live our lives. It owes more to Malthus than to Darwin.
But Darwin's theory is Malthus applied to biology:
"In October 1838, that is, fifteen months after I had begun my systematic inquiry, I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long- continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The results of this would be the formation of a new species. Here, then I had at last got a theory by which to work".
Charles Darwin, from his autobiography. (1876)
I'd argue that the Social Darwinists and evolutionary psychologists (Revol is perfectly right to equate them) have got Darwin right. The problem is with Darwin himself, he can't be excused by blaming his followers, as for instance in titles like
Alas Poor Darwin. Darwin is not some misappropriated colossus; the same logical absurdities and political problems we find in evolutionary psychology are found in Darwin's biology. Darwin's unidirectional, monocausal approach is reductive and undialectical, and therefore manifestly false to the philosophically literate.
Attempts to point this out are generally shouted down with accusations of creationism. Such intolerance is highly revealing, both of the weakness of Darwin's theory and of the political investments that have been made in that theory.
Let's not bother with memetics eh?