If [college boys and girls] leave college thinking, as they usually do, that science offers a full, accurate, and literal description of man and Nature; if they think scientific research by itself yields final answers to social problems; if they think scientists are the only honest, patient, and careful workers in the world; if they think that Copernicus, Galileo, Newton, Lavoisier, and Farady were unimaginative plodders like their own instructors; if they think theories spring from facts and that scientific authority at any time is infallible...and if they think that science steadily and automatically makes for a better world--then they have wasted their time in the science lecture room...they are a menace whether they believe all this by virtue of being engaged in scientific work themselves or of being disqualified from it by felt or fancied incapacity (Liberty Fund edition, 129-130).
Barzun goes on to suggest that students should be taught not just about the theories put forth by scientists like Copernicus, Galileo, and Newton, but about how and why these men labored at what they did, in order to understand that science is not immaterial truth but rather a recent construct of humans. This is not to say that scientists' theories don't represent valuable approximations of how nature works but rather just to remind us all that scientific principles are not immutable truth.
Barzun worries at the same time that the discipline of history is marginalized when it should be broadened. He has a beautiful passage about the importance, the necessity of history in the face of accumulating new inter disciplines that seek to supplant its study:
One can safely generalize and say that under the name of social science, sociology, psychology, anthropology, and economics, many American students today are really offered one single and quite unnecessary subject, namely: Tautology.
History--by which I mean history properly taught--aims at the diametrically opposite results. It is never tautological, it is not confined to one experience or one set of experiences, it does not ape the tricks of physical science; it does not offer brisk formulas for human behavior or pat answers to social problems. But it makes its students think maturely about all the valuable fragments of experience which may have found their way into these latter and shoddier substitutes (152).
Barzun adds "I am not criticizing serious teaching in psychology nor responsible work in sociology under true masters. I have no quarrel with other independent disciplines, but only with the Ersatz that is put forward as fit to supplant history" (152).
Students should be introduced to science and history as somewhat opposite frames with which to view the world--the former finding it quantifiable and predictable, the latter finding it a host for a series of unique events that are nonetheless edifying for its student. Both frames of mind are important for understanding the world, at least as best as one possibly could. What is so valuable about the historical frame of mind is that it lessens one's idealism and cynicism both. As Barzun says:
When broadly based on a good knowledge of western European history (including that of the United States), the historical sense is a comforter and a guide. The possessor understands his neighbors, his government, and the limitations of mankind much better. He knows more clearly not what is desirable but what is possible. He becomes 'practical' in the lasting sense of being taken in neither by panicky fears nor by second-rate Utopias. It is always some illusion that creates disillusion, especially among the young, for whom the only alternative is cynicism. The historical sense is a preventive against both extremes. It is a moderator which insists on knowing conditions before passing judgements. The historical sense is above all political-minded. It suggests that in the struggles of men with one another, no virtue implies the possession of any other; that motives are mixed, and that no evil is absolutely perverse. For these reasons, the study of history tends to make men more tolerant, without on that account weakening their determination to follow the right: they know to well the odds against it [emphasis mine] (155).