His inaugural dissertation was on the notions of political economy among the Romans (Dissertatio exhibens sententias Romanorum ad oeconomiam politicam pertinentes, Erlangen, 1823).
From the year 1836 he acted as inspector of technical instruction in Bavaria, and made frequent journeys to Berlin and Paris in order to study the methods there pursued.
In 1837 he was placed on the council for superintendence of church and school work; in 1839 he was entrusted with the direction of the bureau of statistics; in 1845 he was one of the councillors for the interior.
In this assembly Hermann, with Johann Heckscher and others, was mainly instrumental in organizing the so-called "Great German" party, and was selected as one of the representatives of their views at Vienna.
Warmly supporting the customs union (Zollverein), he acted in 1851 as one of its commissioners at the great industrial exhibition at London, and published an elaborate report on the woollen goods.
From 1835 to 1847 he contributed a long series of reviews, mainly of works on economical subjects, to the Münchener gelehrte Anzeigen and also wrote for Rau's Archiv der politischen Ökonomie and the Augsburger allgemeine Zeitung.
As head of the bureau of statistics he published a series of valuable annual reports (Beiträge zur Statistik des Königreichs Bayern, Hefte 1-17, 1850–1867).
Some thought Hermann's approach allowed the clear rendering of the position of a pure theory of economic facts as an indispensable and independent branch of social science, as opposed to the historic method of inquiry, which was seen as fatal to much that was regarded as distinctive of the abstract or English school of political economy.
Hermann's approach, and that of the writers of continental Europe who followed him, was thus seen as harmonizing perfectly with the theory of the elementary facts from which economical development takes its start.
The influence of this economical principle, the institutions to which it gives rise, the conditions under which it is possible, and the circumstances which affect, modify, or counteract it, are traced with reference to the individual, the family, the community, and the state or nation.
Economics is therefore defined by Hermann as the “quantitative theory of goods;” and, though he is sparing in the use of symbols, his method of treatment is throughout mathematical.
Capital is defined so as to include land, but careful reference is made to the distinctive peculiarities of this form of wealth.
Under fixed capital a very elaborate treatment of the nature and economic influence of machines is given, while the handling of changes in the cost of production, both here and in the essay on “Profit,” is acute and luminous.
On practical questions, those of economic legislation, his opinions are only to be gathered with difficulty from the papers in the Gelehrte Anzeigen, and generally were expressed with such reference to special circumstances as to render doubtful their full import.
It seems probable, however, that his views on protection were far from clear, and that he was somewhat under the sway of the principle that the best financial policy is encouragement of national industry.