From From Dawn to Decadence: 500 Years of Western Cultural Life by Jacques Barzun, 2000, HarperCollins, New York, p 218.
Ten succinct paragraphs of the Pensées state [the warning against scientism] with finality. Scientism is the fallacy of believing that the method of science must be used on all forms of experience and, given time, will settle every issue. Again and again, the bright thought has occurred, “If we can only define our terms, if we can only find the basic unit, if we can spot the right ‘indicators,’ we can then measure and reason flawlessly, we shall have created one more science.” And nearly as often, the shout has been heard: “Eureka! We are scientists,” the new science being some portion of the desired Science of Man—history, sociology, psychology, archaeology, linguistics, and other more or less short-lived ologies…
The motives behind scientism are culturally significant. They have been mixed, as usual; genuine curiosity in search of truth; the rage for certainty and for unity; and the snobbish desire to earn the label scientist when that became a high social and intellectual rank. But these efforts, even though in vain, have not been without harm, to the inventors and to the world at large. The “findings” have inspired policies affecting daily life that were enforced with the same absolute assurance as earlier ones based on religion…The case of Karl Marx is typical. Infatuated with the kudos of science, he persuaded himself and his millions of followers in and out of the Soviet Union that he had at last formulated the mechanics of history and could predict the future scientifically.
Curiously, the only Marxists left have all joined jobs programs (so fertile at providing employment for all manner of politically desirable groups) at Western universities. There they plot their bloody revenge. Never mind.
And from Pascal himself, these:
“The vanity of the sciences.—Physical science will not console me for the ignorance of morality in the time of affliction. But the science of ethics will always console me for the ignorance of the physical sciences.”
“The world is a good judge of things, for it is in natural ignorance, which is man’s true state. The sciences have two extremes which meet. The first is the pure natural ignorance in which all men find themselves at birth. The other extreme is that reached by great intellects, who, having run through all that men can know, find they know nothing, and come back again to that same ignorance from which they set out; but this is a learned ignorance which is conscious of itself. Those between the two, who have departed from natural ignorance and not been able to reach the other, have some smattering of this vain knowledge, and pretend to be wise. These trouble the world, and are bad judges of everything. The people and the wise constitute the world; these despise it, and are despised. They judge badly of everything, and the world judges rightly of them.”