Positivism was a philosophical/scientific movement begun in the 19th century by the sociologist Auguste Comte. Its firm objective was to overcome pre-scientific thinking of all kinds so that the mind of man might advance to a new, fully grounded state of knowledge.

Barfield defines positivism as "the dogma that nothing really exists except what is actually or notionally perceptible by the senses" (EC 6). "It is implicit in positivism," he writes in "The Rediscovery of Meaning," "that man can never really know anything about his specifically human self--his own inner being--anymore than he can ever really know anything about the meaning of the world of nature by which he is surrounded" (RM 12). Its influence has been pervasive. ("It is no part of my case," Barfield concedes, "that push-and-pull empiricism is weak or ineffectual, only that it is, like other giants, ignorant" [PD 35-36].)

Positivism is not usually stated but rather just assumed. "The conclusions of positivism remain concealed (or perhaps 'occult' is the word) as habit, even where its premises have been explicitly abandoned as theory" (EC 18-19). Sometimes, a thinker may remain positivistic in whole or in part without even being conscious of the fact--a phenomenon Barfield describes as R.U.P. (Residue of Unresolved Positivism).

Barfield liked to imagine the changes in human thought that might accompany the demise of positivism.

If we substitute positivism for Aristotelianism, we may get some idea of what is in store for us when we first begin to cast doubts on [positivism as the Renaissance did on the tenets of Aristotelianism]. For it is a mistake to suppose that we are more open-minded today; we are merely open-minded about different things" (RM 14).

And once we find ourselves rid of the last traces of our positivist world view,

we find ourselves with a nature very different from the nature assumed by the evolutionists. But the odd thing is that, once one has got over the shock, this nature turns out to be more, not less, like the nature we actually see, hear, and smell and generally experience around us--easier, not harder, to believe in than theirs! (SM 112).

See in particular "The Evolution Complex," "The Rediscovery of Meaning" (RM 11-21), Worlds Apart, passim.