The Trinitarian Theology of Saint Thomas Aquinas - El Camino ...

138 Trinitarian Monotheism
Thus Anselm faults ‘Those contemporary dialecticians (rather, those heretical
dialecticians) who consider universal substances to be merely vocal emanations’.50
On a theological level, the abbot of Bec replies to Roscelin by making
a distinction between that which is common within God (the divine essence)
and that which is distinct (the persons and their properties). The three
persons are one single res (substance or essence); if one chooses to speak of
three res, one can only be making the word ‘res’ stand for the relations, not the
substance.51 Anselm retraced the main steps of his reply in a letter addressed
to Foulques, bishop of Beauvais, to be read before the assembled Council of
Soissons (1092); the council would condemn Roscelin’s erroneous conception
of the Trinity.
Abelard also reacted against Roscelin’s thesis. In a letter sent to the bishop
of Paris around 1120, the Master of Pallet explained that the principal aim of
his writings on the Trinity was to refute Roscelin’s tritheism, condemned by
the Council of Soissons.52 The Theologia Summi Boni (and its later elaborations,
the Theologia Christiana and the Theologia Scholarium) aim to furnish
a defence of traditional Trinitarian doctrine in response to the new ‘dialecticians’.
In his own thesis, Abelard developed an understanding of the Father,
Son, and Holy Spirit by means of the attributes of power, wisdom, and
goodness: we will return to it in connection with the theory of appropriations.53
Abelard avoids the perils of tritheism by excluding numerical plurality
from God. So, he does not accept that one can speak of God as being
‘three’ or ‘many’ (multa) in an unqualiWed way: God is ‘many persons’, but he
is not ‘many’, and there is, ‘in an absolute sense’, no ‘three’ (tria per se) in God.
For Abelard, preWxing ‘three’ to ‘persons’, in the phrase ‘three persons’ is
accidental (accidentaliter). Properly speaking, the number is not applicable to
God. Because he was quite clearly taking into account only the numerical
terms which derive from quantity, Abelard rejects numerical plurality in God
and excludes the idea that there is in God a ‘three in an absolute sense’. There
is a multiplicity of properties or of ‘deWnitions’ but there is neither numerical
plurality nor diversity in God.54 Thus, it was Abelard who opened the
question of ‘numerical terms’ within scholastic Trinitarian theology.
50 Anselm, Epistola de incarnatione Verbi (2nd version), in Anselm of Canterbury: The Major
Works, ed. Brian Davies and G. R. Evans, Oxford, 1998, p. 237; Evans and Davies have ‘logicians’, not
‘dialecticians’. Roscelin’s nominalism or ‘vocalism’ (which claims that only words or vocal sounds
and singular things exist) is considered to have been the starting-point for the debate about
universals; cf. A. de Libera, La querelle des universaux de Platon à la Wn du Moyen Age, Paris, 1996,
pp. 142–146.
51 Anselm, Epistola de incarnatione Verbi, ch. 2.
52 C. J. Mews, ‘Introduction’, in Petri Abaelardi Theologia ‘Summi Boni ’, CCCM 13, Turnhout,
1987, p. 39; cf. PL 178. 355–358.
53 See below, in Chapter 13, ‘The origins of the Idea of Appropriations’.
54 Abelard, Theologia Summi Boni, Book III, ch. I, nos. 5–7 (CCCM 13, pp. 159–161).