That’s a direct rejection of science as a valid way of understanding the world (obviously, we live in a physical world, not in a “social science” one), stated as explicitly as you will ever hear it. It doesn’t originate with Bradley, one of the most often quoted examples of what complete idiots economists really are is pretty much the same statement coming from Milton Friedman, and he may not be the first one either, I have not been particularly persistent in tracking down the origins of it and it doesn’t really matter.
Barry Commoner has criticized Ehrlich's 1970 statement that "When you reach a point where you realize further efforts will be futile, you may as well look after yourself and your friends and enjoy what little time you have left. That point for me is 1972."  Gardner has criticized Ehrlich for endorsing the strategies proposed by William and Paul Paddock in their book Famine 1975! . They had proposed a system of "triage" that would end food aid to "hopeless" countries such as India and Egypt. In Population Bomb , Ehrlich suggests that "there is no rational choice except to adopt some form of the Paddocks' strategy as far as food distribution is concerned." Had this strategy been implemented for countries such as India and Egypt, which were reliant on food aid at that time, they would almost certainly have suffered famines.  Instead, both Egypt and India have greatly increased their food production and now feed much larger populations without reliance on food aid.