104 Popes and Jews, 1095–1291
twelfth-century Decretum examined questions about Church discipline, collected
authoritative texts including canons of Church councils, opinions of early Church
fathers and papal pronouncements, as well as providing an intellectual framework
within which contradictions could be resolved.13 The selection of texts in the
Decretum depended heavily on the works of earlier canonists, and although the
collection and commentary, as opposed to the basic texts which it contained, had
no formal status in the Church, it was highly influential in moulding the attitudes
of canon lawyers, senior churchmen, and popes. In particular it contained important
material from the Church fathers and earlier popes concerned with the justifica-
tion of violence in a good cause as well as the status of Muslims, heretics, and Jews
in Christian society.14
Yet although the Decretum was compiled almost fifty years after Urban II
launched the First Crusade in 1095, no part of it was specifically devoted to cru-
sades. Thus Causa (Case Study) 17 dealt with the canonical status of a vow and its
implications, but made no mention of the crusade vow in particular.15 This was
probably because most texts it cited were pre-twelfth century and much of gratian’s
thinking was shaped by the earlier work of canon lawyers such as Anselm II of
Lucca and Ivo of Chartres writing just prior to the First Crusade.16 Nevertheless,
despite the fact that there was no specific treatment of crusades, it remained an
important text for the later development of the idea of crusading because it elab-
orated on the canonical tradition, stemming from the early Church, about just
violence and just wars. Thirteenth-century crusade preachers who regarded crusades
as one type of just war frequently cited it in their sermons.
Causa 23 of the Decretum was particularly pertinent to popes’ authorization of
military campaigns against those perceived as enemies of the Church because it
enquired as to whether violence could ever be considered just.17 It treated the
hypothetical case of certain heretical bishops who had begun to compel neigh-
bouring Catholics under threat of torture to espouse their beliefs and the response
of a pope who ordered the loyal bishops to defend these Catholics and compel the
heretics to return to the Faith. Subsequently the Catholic bishops sent soldiers to
round up the heretics who were then executed, deprived of their possessions or
ecclesiastical appointments, or imprisoned until they recanted. The complexity of
the case, the number of ‘Quaestiones’ (‘questions’) raised, and the fact that many of
the answers which provided the basic justification for force were extracts from the
writings of Church fathers—in particular from the letters of St Augustine—were
now claimed to demonstrate that war was not intrinsically sinful and that some
wars were more moral than others. Hence the case emphasized the intricate prob-
lems connected with the authorizing of violence in what the Church considered
a just cause.
13 Gratian, passim.
14 rebecca rist, The Papacy and Crusading in Europe, 1198–1245 (London, 2009), pp.6–7.
15 James Brundage, Medieval Canon Law and the Crusader (Madison, London, 1969), pp.40–5.
16 Jonathan riley-Smith, The First Crusade and the Idea of Crusading (London, 1986), pp.5–7.
17 Gratian, ‘Causa 23’, cols 889–965.