‘Radicalism’ has become an established term with regard to the late eighteenth-century movement for political reform in England, whereas the term radicalisme is not normally used to designate a particular political group during the French Revolution. We are wont to speak of a radicalisation of the Revolution. But the radicals themselves we call Jacobins, sans-culottes or some other contemporaneous name. Any attempt to compare English and French radicalism in the period of the French Revolution should therefore make clear to which political currents it refers.
The term ‘radicalism’ enters the political language(s) of Europe during the opening decades of the nineteenth century. It seems to have been first used in Britain, from where it migrated to France during the 1820s and via France to Germany during the 1830s. Just like the term ‘conservative’ which appeared at about the same time, it was used to describe a particular way of dealing with the political heritage of the eighteenth-century revolution in government. Whereas the adjective ‘radical’ came eventually to be used in a politically neutral sense, the noun never lost the original semantic link with the later eighteenth-century demand to enforce the principle of government by consent without any social reservation. Uncompromising conservatives were never called radicals but found themselves, equally tellingly, labelled die-hards or ultras. A radical was someone who adhered unflinchingly to the leading principles of what Robert Palmer has named the ‘democratic revolution’ of the later eighteenth century.