This thesis show how the concept of association in France, in the answers to the “social question” to XIXe and XXe century, was polarized by the two dominant ways of justification : liberalism and Welfare State. At the XIXe century, we show how association's concept mainly thinks in articulation with the liberalism and at the XXe century how it thinks in bond with Welfare State. But for each one of these periods, association was not folded back on one of these dominant ways of justification, she brings an innovation's capacity. The term of polarization was selected meaning by there association is never folded one of these dominant ways of justification but only attract, she keep an autonomy : at the XIXe century, association supplements the...