Handbook of the History of Logic: - Fordham University Faculty

The Latin Tradition of Logic to 1100 43
5 THE ELEVENTH CENTURY: LOGIC AND THEOLOGY
From the evidence of manuscripts copied, and especially from the position that
had been reached by c. 1100, it is clear the eleventh century was a time when the
developments in logic of the later tenth century became widespread and were taken
further. By the end of the century, the thorough study of the core texts of the logica
vetus — Porphyry’s Isagoge, Aristotle’s Categories and On Interpretation, and
Boethius’s text-books on categorical and hypothetical syllogisms, division and the
topics — had become established, at least at the leading schools, and logicians were
launching themselves into the interpretative problems stimulated by Boethius’s
commentaries and by the parallels and discordances with the Stoic semantics found
in Priscian’s Grammatical Institutions (Institutiones grammaticae), a work much
studied in this period. There is, however, a surprising lack of purely logical texts
that can be dated to the eleventh century. Garlandus’s Dialectic, once dated to
before 1050, is now recognized as the work of Garlandus of Besançon, and may well
have been written later than 1110 or even than 1120. In cataloguing the continuous
commentaries to the Isagoge, Categories and On Interpretation, I found none for
which there is compelling evidence of its being written before 1100 [Marenbon,
2000b]; Green-Pedersen [1984, 147-53, 418-9] suggests that two or three surviving
commentaries on De topicis differentiis may be a few years earlier, but without
decisive proof. Since, as the next chapter will explain, these commentaries are
layered compositions, it is extremely probable that the earliest layer or layers go
back to before the time of the earliest manuscripts, but it is impossible to discern
exactly what material belonged to these first forms of the commentaries.
For logic in the eleventh century, then, we must look to four thinkers who used
it especially in connection with theology: Lanfranc and Berengar, in their dispute
over the Eucharist; Peter Damian, in discussing whether God can undo the past;
and Anselm, who was also responsible for two ostensibly non-theological logical
discussions. 2
5.1 Logic and the Eucharist: Lanfranc and Berengar
([Holopainen, 1996, 44-118; Marenbon, 2005a, 232-7])
In the sacrament of the Eucharist, Christians maintain that the bread and wine
blessed by the priest are the body and blood of Jesus Christ. Berengar of Tours,
writing in the middle of the eleventh century, maintained that this identity must
be understood just in terms of signification. The priest’s words of consecration
do indeed bring about a change, but it is to make the bread and wine into signs
for Christ’s body and blood. But there is no change in the substance of the
bread and wine, and if there were — Berengar maintains — then they could no
2 The greater part of Odo of Tournai’s treatise De peccato originali [in Patrologia Latina 160,
1071-1102; trsl. Odo of Tournai, 1994] is concerned with the problem of universals (see [Erismann,
Forthcoming-A, and Forthcoming-B]). Since it was not written until 1095 at the earliest, and
perhaps as late as 1110, and its concerns are intimately linked to the discussions of the early
1100s, it is better discussed in the context of the next chapter.