The connection between constructivist rationalism (the construction of morality from scratch) and socialist thought, Hayek argues, is that they both flow from conceiving order as arrangement and control on the basis of accumulation of all the facts. But, as Hayek earlier showed in his landmark 1945 essay, "The Use of Knowledge in Society", the extended order could not be such an order, for accumulation of all the requisite facts is simply impossible. Now he asserts that, similarly, the practices of traditional morality not only do not, but cannot, meet the requirements or criteria demanded by scientism. Hence they are necessarily "unreasonable" and "unscientific". Hayek insists, though, that this is not "news", for David Hume (1711-76) observed centuries ago that "the rules of morality are not the conclusions of our reason".
And this is not simply the case with traditional morals (including God, sex, family, and — particularly of interest to Hayek — private property, saving, exchange, honesty, truthfulness and contract), but "is also true of any possible moral code, including any that socialists might ever be able to come up with". Hence were we to pursue this perilous path — as "all versions of scientism have advised" — we would soon "be back at the level of the savage who trusts only his instincts". No argument about morals, therefore, can legitimately turn on the issue of scientific justification, because it cannot be achieved, so nothing can be gained-but everything can be lost.