On the natural generation of human beings: the vegetative power in a thought experiment by some masters of arts (1250-c. 1268)

This paper focusses on a thought experiment devised by some Masters of Arts (John de Sècheville, De principiis naturae, 1956, 128–131; Anonymi Magistri Artium Quaestiones super librum de anima, ed. P. Bernardini, 2009, q. 60; Ps.-Petrus Guentin de Ortemberg, Quaestiones super Physicam, II, q. 1, mss. London, Wellcome Hist. Med. Libr., 333, fols. 26rb-27va; Firenze, Bibl. Naz. Centr., Conv. Soppr. A.V.563, fols. 29rb-31ra) in three works devoted to naturalistic issues and composed around 1250–1268. The experiment concerns the possibility that the human species be transmitted just by natural generation, that is thanks to the vegetative power rooted in the human being and without any need for God’s intervention. The experiment belongs to the set of arguments employed by the Masters in support of the thesis of the natural specific difference of man. Such a thesis was judged heretical and included in the Parisian Syllabus of 1277 (see art. 113: a human being is a human being independently of the rational soul). The three texts examined here show a strikingly naturalistic approach, which is deeply in contrast with both the common view of contemporary Masters of Arts and standard thirteenth-century theological theories of human generation.