Ninth in a series of fourteen posts (1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, & 14).
In my previous post on this topic, I said that 'scientism' was used several times during the 1870s in response to the works of T. H. Huxley and John Tyndall. These two scientists belonged to the the X Club, which (according to Ruth Barton) aimed to weaken the Church of England's influence over scientific institutions.
The use of 'scientism' increased after 1874, the year of Tyndall's Belfast Address. 1874 was also the year in which Huxley published 'On the Hypothesis that Animals are Automata', which he apparently presented at the same Belfast meeting at which Tyndall spoke (although this source says that Huxley gave the talk in 1870 and only published it in 1874). Tyndall's address and Huxley's 'Hypothesis' each provoked widespread controversy and debate in British and American journals and surely must have played an important role in the spread of the cry 'Scientism!'
I said (in post # 8 of this series) that the label 'scientism' was at first applied not to positivists but, instead, to the supposed materialists in the X Club. In spite of their shared enthusiasm for the sciences, the positivists and X-Clubbers were not on friendly terms with each other. Huxley had called Comte's positivism 'Catholicism minus Christianity'; he classed positivism among the 'sickening humbugs'; and Huxley had a vigorous debate with the positivist Frederic Harrison, whose criticisms of materialism included some thinly veiled ad hominems directed at Huxley. (Another X-Club member, Herbert Spencer, produced his own critique of Comte.)
I would have expected the positivists to be the first to be charged with scientism. As we have seen, 'scientism' sometimes carries the connotation that one adheres to a new, secular worldview, a comprehensive framework of belief that is meant to replace religion and that purports to be built upon science; and it was Comte, after all, who called for an actual 'religion of humanity'. Moreover, the English positivists actually did build a secular church (or two).
But in the 1870s, it was members of the X Club (and some of its invited speakers, such as W. K. Clifford) who were said to be guilty of scientism. The term seems to have been meant to impute, first, an epistemology. In the rhetorical excesses of its critics, adherents of scientism were sometimes represented as believing that the methods of science would give us exhaustive knowledge of reality. However, no one in the X Club can reasonably be interpreted as having championed such a hubristic epistemology. At most, Huxley and the others adopted the more modest view that insofar as something can be known (more accurately, known about) at all, it can be known only via the methods of science.
As I noted in post # 8, the metaphysics that scientism allegedly implied drew much of the fire from critics in the early and mid-1870s, and this metaphysics was materialism. According to the critics, scientism's proponents took reality to be nothing beyond the world revealed by science, and every part of that world was (supposedly) either physical or entirely dependent on physical things. (The latter disjunct accommodates Huxley's psychological model in which mental events aren't physical but are mere by-products, epiphenomena, of a material system.) The critics thus portrayed scientism as being wedded to a materialistic metaphysics in which everything is material or dependent on material things. More plausibly, though, the X-Clubbers and their allies made only the more modest claim that everything
encompassed by our knowledge (thus far) is material or is dependent upon material things.
(In fact, Huxley's views on materialism and metaphysics were much more complicated than his critics implied [as Sherri Lyons has argued]. Tyndall was impressed by the explanatory gap between consciousness and physical states (à la du Bois-Reymond; more here) and may have been an idealist; he was influenced by Kant, Fichte, F. Schlegel, Carlyle, and Emerson [as Ruth Barton and others have stressed]. And Spencer, also aware of the explanatory gap, opted for the 'Unknown Reality' of neutral monism [see the final paragraph of his 'First Principles'].)
So, in the late Nineteenth Century, 'scientism' was used by defenders of Christianity as a label for an epistemological and metaphysical outlook that affords no support for traditional theistic belief. Most of those who were charged with scientism belonged to the X Club, which had challenged the institutional power of the Church of England. The phrase 'scientism' was used to mark these individuals as materialists.
Here's a rough stab at a definition of 'scientism' (as used by its 1870s critics): Scientism is the doctrine that all beliefs about the nature of reality should be warranted by the methods of the natural sciences; the result of this epistemic policy is materialism.
The X-Clubbers would perhaps balk at the suggestion that they had advanced any such prescription for forming beliefs about the nature of reality (the really real, the basic furniture of the universe, etc.). That's metaphysics, after all, which they eschew in favour of agnosticism. They stick to the observable phenomena. Of course, this response would not placate their critics, who would take Huxley and the others still to be committed to the doctrine that any beliefs we may form about the world -- whether about its ultimate nature or about the terrain through which we navigate in our daily lives (or about the mechanisms that explain the phenomena in that terrain) -- should be justified by the methods of the natural sciences, a policy which yields a materialistic picture of the known world and agnosticism about whether there's anything more. The critics would also argue that this scientistic doctrine cannot itself be supported by means of natural-scientific method.
These early uses of 'scientism' don't share the political connotations that attended the term's mid-20th-Century uses. Indeed, the X-Clubbers generally opposed socialism. Perhaps the 20th-Century association of scientism with socialist views was a product of French influence, but that's sheer speculation on my part.