Manlii Seuerini Boetii, Opera omnia, accurante J.-P. Migne, tomus posterior, Parisiis 1891, 761-794 (Patrologiae Latinae, 64)
The title given to this work in Migne’s edition suggests that it is concerned with categorical syllogisms; in fact, the Introductio - like the first book of the De syllogismo categorico - analyzes propositions, the elements comprising them, and their possible conversions. Boethius nevertheless claims that the Introductio is an essay that addresses categorical syllogisms (PL 64.762), a fact suggesting that the work is incomplete and that the author may have planned to analyze categorical syllogisms in a hypothetical second book that was never actually written (Marenbon 2003). It is thus possible that the Introductio represents the start of a second version of the De syllogismo categorico: the two essays address the same themes, but the analysis offered by the Introductio is more complete and detailed; moreover, certain features of the manuscript tradition suggest that the Introductio was never revised for final publication and that it remained in draft form when it began to be copied (Thomsen 2008).
There is little manuscript evidence for the title that Migne gave to this work: the oldest codices use the title “Introductio ad syllogismos categoricos” in reference to the De syllogismo categorico, and instead call the Introductio “Antepraedicamenta,” a Latin calque of the Greek προλεγόμενα (Van de Vyver 1929). One manuscript (Wien, Österreich. Nationalbibl. 2269) calls the Introductio In priora ante praedicamenta, presumably a corrupt transmission of In priora <analytica> praedicenda (De Rijk 1964).
The argument of the treatise follows a logical progression from simple to complex: names and predicates make up phrases that, in turn, comprise syllogisms. Boethius, however, analyzes the propositiones by proceeding through successive distinctions, a modus operandi that had already been used in the commentaries of Alexander of Aphrodisias, Ammonius, and Philoponus. The treatment of conversiones found in the Introductio differs from its Greek models and from the De syllogismo categorico in that Boethius presents two additional types of conversio per oppositionem: one based on switching the order of the terms and another based on negating either the subject or the predicate (Lee 1984).
There have been many attempts to analyze the relationship between the De syllogismo categorico and the Introductio ad syllogismos categoricos, as well as to determine their relative chronology. Of special interest has been the function of these two works within Boethius’ larger corpus of logical treatises (Thomsen 2008). Cross-references suggest that the Introductio, like the De syllogismo categorico, can be ascribed to the period between the redactions of Boethius’ first and second commentaries on the Peri hermeneias: in the introductio, Boethius refers explicitly to his commentary on the Peri hermeneias (though we do not know which of the two he means), directing his reader there for a more detailed analysis of nomina (PL 64.764). On the other hand, the first commentary on the Peri hermeneias does not refer to any treatise concerned with categorical syllogisms, while the second commentary alludes to books “quos de categoricis syllogismis composuimus” (In Peri herm. 2.172.8).
The text of the Introductio ad syllogismos categoricos is transmitted by about 20 manuscripts that have been dated between the 10th and 15th c. The work was rediscovered at the start of the Late Medieval period and enjoyed its greatest diffusion in the 12th c. Only two codices report the text of the Introductio by itself, i.e. decoupled from the De syllogismo categorico. This fact suggests that the Introductio had a narrower diffusion than the other treatise (Thomsen 2008). [M. Ferroni; tr. C. L. Caterine].