Marsilius of Padua (1275/80–1342/3)

Marsilius of Padua’s Defensor pacis (Defender of Peace), written in 1324, is the most revolutionary political treatise of the later Middle Ages. Discourse One of the Defensor pacis can plausibly be read as a complete theory of the secular state. In a much longer second discourse, Marsilius attacks papal and priestly political power, which, especially in the claims to ‘fullness of power’ (plenitudo potestatis) sometimes made for the papacy, he presents as a major threat to civic tranquillity. The distinctive features of Marsilian theory are (a) its emphasis on broad participation in the legislative process as a guarantee of sound law, and (b) its insistence that supreme coercive power in any community must be held by a single, secular, popularly authorized ‘ruling part’ (pars principans).