The book paints Herbert Spencer as the eugenics-championing bad guy and posits that Darwin and Darwinism had little influence on Hitler’s master race ethic.
Ideas do indeed have consequences, but not all ideas play out the same way or weave their way in the history of ideas toward the same destination.
O’Connell and Ruse’s failure to engage deeply and fully with the historiography of this question makes it hard to take their effort seriously.
The authors imply that social Darwinism was a position taken by non-scientists who just didn’t understand the science.
I have clearly argued in all my works that Hitler was an eclectic thinker who drew on many different intellectual influences — some of them contradictory.