quality:corruption, structural:expansion
Charles Gide's economic theory

Solidarity also played a central role in the thinking of the French economist Charles Gide (1847–1932). Gide set out to challenge the dominance of the liberal school of economics in France. His thinking was influenced by both biology and sociology. He was particularly influenced by Charles Fourier, who had criticised the social ills created by free market competition. Solidarity became a fundamental concept in Gide's thinking. He found manifestations of solidarity in nature, in the economy and in the social interdependencies of society, but for him solidarity was only ethically valuable when it was consciously voluntary. He created his own national economic doctrine, called Solidarism, according to which society could gradually move towards a cooperative economy in which workers themselves controlled the means of production. In Gide's thinking, the values and goals of solidarity could be pursued through cooperative associations, 'the voluntary association of well-meaning people'.

In Gide's solidarity, the common property created by free cooperative associations is their own and the added value created by their activities is returned in the form of profit sharing. Solidarism preserved the foundations of the free market economic system and also accepted differences in people's economic status. However, large income disparities were not in line with the idea of solidarity, as Gide considered them to break the ties that bind the individual to society. Gide is considered a major representative of the French historical school, and his ideas were quite different from the mainstream liberal economics of the time. Gide's social philosophy was close to that of Léon Walras, the developer of neoclassical general equilibrium theory, and he was one of the few supporters of Walras during his lifetime.

Solidarity is still the core value underlying cooperatives today, alongside self-reliance, ownership, equality and justice. Cooperative members have a duty to emphasise the common interest and to ensure that all members are treated as fairly as possible. In addition to solidarity with its own members, the cooperative now also emphasises social responsibility beyond the cooperative itself.