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Relational inferences are a well-known problem for Aristotelian logic. This book charts the development of thinking about this anomaly, from the beginnings of the Arabic logical tradition in the tenth century to the end of the nineteenth. Based in large part on hitherto unstudied manuscripts and rare books, the study shows that the problem of relational inferences was vigorously debated in the thirteenth, fourteenth and fifteenth centuries. In the course of the seventeenth and eighteenth centuries, Ottoman logicians (writing in Arabic) came to recognize relational inferences as a distinct kind of 'unfamiliar syllogism' and began to investigate their logic. These findings show that the development of Arabic logic did not - as is often supposed - come to an end in the fourteenth century. On the contrary, Arabic logic was still being developed by critical and fecund reflections as late as the eighteenth and nineteenth centuries.

The present article traces the controversy on propositions and their parts, intensively discussed by logicians writing in Arabic in the fourteenth, fifteenth and sixteenth centuries. From the beginning of the Arabic logical tradition to the end of the thirteenth century, the dominant view among Arabic logicians was that a categorical proposition consists of three parts: subject, predicate and nexus between them indicated (in most languages) by the copula. A number of influential logicians from the fourteenth century suggested that the parts are strictly four: the subject, the predicate, the nexus between them, and the judgment. This thesis was criticized in the late fifteenth century, most influentially by the Persian scholar Dawānī (d.1502). His criticism and the ensuing discussion came to be intertwined with another controversial issue: can some objects of conception (taṣawwur) also be objects of assent (taṣdīq)?

In: Oriens