In the spring of 1792, he received the rank of maréchal de camp in command of the cavalry in the army of the north, but the influence of the extremists becoming predominant he took indefinite leave of absence and settled at Auteuil, where with Condorcet and Cabanis he devoted himself to scientific studies.

[1] Under the Reign of Terror, he was arrested and imprisoned for nearly a year, during which he studied Étienne Bonnot de Condillac and John Locke and abandoned the natural sciences for philosophy.

He soon began to attract attention by the memoires which he read before his colleagues—papers which formed the first draft of his comprehensive work on ideology, named Eléments d'idéologie.

[1] Considered for the influences of his philosophy, de Tracy minimally deserves credit for his distinction between active and passive touch which ultimately fed the development of psychological theories of muscular sense.

His account of the notion of external existence as being derived not from pure sensation, but from the experience of action on the one hand and resistance on the other, stands in this light to be compared with the works of Alexander Bain and later psychologists.

[1] His chief works are the five-volume Éléments d'idéologie (1817–1818), the first volume of which was presented as "Ideology Strictly Defined" and which completed the arguments made in earlier completed monographs; Commentaire sur l'esprit des lois de Montesquieu (1806) and Essai sur le génie, et les ouvrages de Montesquieu (1808).

[1] The fourth volume of the Eléments d'idéologie the author regarded as the introduction to a second section of the planned nine-part work[5] which he titled Traité de la volonté (Treatise on the Will and Its Effects).

[7] Tracy's influence can be seen both on the Continent (particularly on Stendhal, Augustin Thierry, Auguste Comte and Charles Dunoyer) and in the United States, where the general approach of the French Liberal School of political economy competed evenly with British classical political economy well until the end of the 19th century as evidenced in the work and reputation of Arthur Latham Perry and others.

This republicanism as well as his advocacy of reason in philosophy and laissez-faire for economic policy lost him favor with Napoleon, who turned Tracy's coinage of "ideology" into a term of abuse.