EN“Ideology”, as an object of knowledge, is subject to very different approaches in different disciplines. The evaluative approach (negative or critical), which makes ideology a blemish of modern societies, dominates the social and political sciences, both of Marxist and anti-Marxist tendencies. A descriptive or “neutral” approach appeared only in the twentieth century, in anthropology and in the human sciences of structural inspiration. A comparison of these perspectives reveals the specificity of the semiotic approach of ideology and its contribution to the social sciences in general.