German historian Reinhart Koselleck claimed that "On the Continent there were two social structures that left a decisive imprint on the Age of Enlightenment: the Republic of Letters and the Masonic lodges." Scottish professor Thomas Munck argues that "although the Masons did promote international and cross-social contacts which were essentially non-religious and broadly in agreement with enlightened values, they can hardly be described as a major radical or reformist network in their own right." Many of the Masons values seemed to greatly appeal to Enlightenment values and thinkers. Diderot discusses the link between Freemason ideals and the enlightenment in D'Alembert's Dream, exploring masonry as a way of spreading enlightenment beliefs. Historian Margaret Jacob stresses the importance of the Masons in indirectly inspiring enlightened political thought. On the negative side, Daniel Roche contests claims that Masonry promoted egalitarianism. He argues that the lodges only attracted men of similar social backgrounds. The presence of noble women in the French "lodges of adoption" that formed in the 1780s was largely due to the close ties shared between these lodges and aristocratic society.

According to German historian Reinhart Koselleck, which two social structures left a decisive imprint on the Age of Enlightenment?