Jonah Goldberg has some follow-up thoughts from his earlier post:
Which brings us to the first emailer, who sees eugenics as “social Darwinism” on speed. I think this a very common way of thinking about social Darwinism and eugenics, and I think it is entirely wrong. The salient point about social Darwinism, as laid out by Herbert Spencer, its chief author and the man who coined the phrase “survival of the fittest,” is that it was an argument for radical libertarianism. Spencer was a passionate foe of statism. He was precisely the “‘Laisser Faire’ individualist” Webb had in mind. This is why it is so infuriating when liberal historians and intellectuals blame Spencer for eugenics, Hitler, etc. Spencer would have been horrified at all that. Why it should continually be news to some liberals is beyond me: but the Nazis were not laissez faire.
The missing piece of the puzzle is what the historian Eric Goldman and others have called “reform Darwinism.” This was the view that Darwinism legitimized state interference on eugenic grounds. Holmes’s expressed desire to use the law to “build a race” was quintessential reform Darwinism. Buck v. Bell was reform Darwinism. Holmes’s ridicule of Spencer in Lochner was perfectly consistent with Holmes’s statism and his reform Darwinism. The problem we have today is that any concept of reform Darwinism has dropped out of the discussion. All people remember is the term “social Darwinism,” which is supposed to describe both Hitlerism (hyper statist) and radical laissez faire (the opposite of hyper statism). Social Darwinism may be bad on any number of fronts (bad politics, bad science, bad philosophy, bad morals, etc.) but it isn’t statist.
Leftists who attempt to distance themselves from Hitler like to emphasize the (trivial) differences between Hitlerism and Stalinism, while ignoring the much more important commonality — both were murderous totalitarianisms, and (as Jonah notes) hyperstatisms. The difference was pretty much transparent to the user. And the notion that Nazism was “right wing” doesn’t sit very well with the notion that libertarianism is. Something has to give in this mindless left/right taxonomy.