Jacopo Zabarella’s Opera Logica was published in Venice in 1578. It immediately gave rise to widespread discussion and argument before becoming a highly popular work not only in Italy but also, and above all, in central and northern Europe, in particular in the «reformed» Protestant universities. This essay is the first in a research into the doctrine of logic in Paduan philosophy, which has already rise to another, already published, study. It is the author’s intention to develop the latter further, but in the meantime the theme discussed here is the «genus» of logic in question. It is a fundamental theme that Zabarella was the first to tackle. He began by asserting that the «definition of the thing» was so obscure that many men of letters, philosophers and logicians had ignored it. The very reason why he proposed to study the «proximate genus » of logic, which can be ascertained by examining the various forms of knowledge. This revealed the existence of five intellectual «habits»: science, prudence, art, intellect and erudition. Analysis of the «habits» and then the «concepts» and «names» enabled him to establish that logic was neither a «science» nor an «art» and certainly could not be confused with «dialectics». Its true nature, in fact, was that of an «instrument of science». This entailed acknowledging its «independence», though one conditioned by the Aristotelian distinction between the world of necessary and immutable «things» and that of human action and endeavour.
Keywords: Zabarella’s logic, «genus» of logic, logic as «instrument of science»