[2][3] His social and political philosophy owed much to his reading of Proudhon, Karl Marx, Giambattista Vico, Henri Bergson[4][5] (whose lectures at the Collège de France he attended), and later William James.

Between 1909 and 1910 he was marginally involved with Charles Maurras' Action Française, and between 1911 and 1913 he wrote for the politically transversal L'Indépendance, established together with Édouard Berth – one of Sorel's main disciples – and Georges Valois, closer to Maurrassian circles.

According to historian Zeev Sternhell, Sorel's revision of Marxism broke the necessity of the link between revolution and working class, opening up the possibility of replacing the proletariat with the national community.

He moved to working on some of France's first Marxist journals ( L’Ère nouvelle and Le Devenir Social) and to participating, on the revisionist side, in the debate launched by Eduard Bernstein.

Through his writings in Enrico Leone's Il Divenire sociale and Hubert Lagardelle's Mouvement socialiste, he contributed around 1905 to the theoretical elaboration of revolutionary syndicalism.

In the wake of the 1909 defeat of the syndicalist wing of the Confédération Générale du Travail (CGT), Sorel became close for a period in 1909–1910 with Charles Maurras’ Action française, while sharing neither its nationalism nor its political program.

Whereas Sorel's support for Bolshevism is a matter of abundant public record, his much-talked-about interest in the newborn fascist movement is only confirmed by nationalist sources from the interwar period.

Often associated with an heroic, apocalyptic, and ultimately aesthetic Marxism, Sorel is by some (for example, Hannah Arendt, 'On Violence') thought more as a thinker of decadence.

Absorbing the twin influences of Henri Bergson and Italian idealists, Sorel elaborated a Marxism rejecting economic and historical determinism, and seeing itself not as social science but as a historically-situated ideology.

[16] In a context in which Marx's work remained relatively unknown and obscure, Sorel sought to develop the theory in order to prove that, as he wrote to Benedetto Croce in 1895, "socialism is worthy of belonging to the modern scientific movement".

Through readings of Giambattista Vico and exchanges with Antonio Labriola and Benedetto Croce, Sorel came to an understanding of Marxism as a theory of class agency embedded in institutions.

He insisted, instead, on the institutional development of the proletariat, on the capacity of unions to become not only sites of resistance to capital, but more importantly spaces in which new, post-capitalist social relations could emerge.

[20]While until 1900 he had believed that this path of institutional development was best served through political engagement in parliamentary democracy, his ideas changed in the beginning of the century.

[22]Generally seen as a representative of fin de siècle irrationalism, Sorel's epistemological thinking is more accurately characterized as anti-positivist and increasingly moving towards a proto-pragmatist position.

Drawing upon Henri Bergson's Time and Free Will, he elaborated a theory of human freedom not as exemption from natural determinism but as creative capacity: "We are free in the sense that we can construct tools that have no model in the cosmic environment; we do not alter the laws of nature, but we are capable of creating sequences whose ordering is our decision"[24] At the same time, however, experimental practice provided to science an anchoring into the deterministic cosmic milieu, and hence could safeguard scientific realism.

That, he could do thanks to the reading of the work of Italian philosopher Giambattista Vico, whose epistemology of verum ipsum factum allowed Sorel to develop an alternative account of what a scientific explanation consists in.

As Sorel noted, this furnishes the epistemological grounding on which a social scientific enterprise can stand, provided that it renounces notions of atemporal laws of historical development and it focuses instead on the situated, contextual, explanation of human collective agency.

Much of the anti-deterministic force of his epistemology found a fruitful channel of expression in Sorel's efforts to revise Marxism in a more agency-oriented fashion.

Nonetheless, as early as the "Study on Vico", he had become aware of the relativistic implications of his epistemology:Thus ideal history has perished, overcome by the development of historical research.

[28] In the first edition of his Illusions of Progress, he calls pragmatism the "last term of bourgeois philosophy", adding that its popularity was due to its "flexibility, its garrulousness, and the cynicism of its success".