Introduction (Cl. Désirat & T. Hordé) The history of sciences often reduces the Ideologists (D. de Tracy, F. Thurot, Volney, etc...) to being, linguistica1ly, the defenders of the then moribund " Grammaire Générale". This special issue of H. E. L. shows that a1though it was never a unified doctrine, either in the sciences of language or in philosophy, Ideology has defined certain metatheorica1 principles (" Ideology is the theory of theories", wrote D. de Tracy) of the organization and the development of the human sciences, at the basis of which grammar, or more precisely, the semiolo · gical component of Ideology (as in Degerando for instance) acts as the epistemological pattern. It is on such principles that the Ideologists, very close to government from 1795 to the Empire, relied when they planned and in part implemented the basis of a school system and of an institutional organization of the sciences (cf. in particular Cabanis and Destutt de Tracy). In linguistics, they not oruy defended " Grammaire Générale" (Tracy tired to include in his Elemens d1deologie the ana1ysis of Beauzée and Condillac) but a1so continued the French anthropological movement in which the comparison of languages was linked with an historica1 and/ or geographical wiewpoint. They also originated a research in the history of linguistics (like Thurot and Volney). All this now opens up a rich field of research for the historians of the language sciences, whose task should be to revea1 the existence and nature of French linguistics in the first half of the nineteenth century, which for decades had Iain hidden beneath the huge number of French school grammars and the success of German comparative grammar.