Handbook of the History of Logic: - Fordham University Faculty

Medieval Modal Theories and Modal Logic 519
asked whether one should apply the notion of possibility without qualification to
divine possibilities and the notion of qualified possibility, such as natural possibility,
to those spoken of in accordance with the lower causes, or vice versa. 38 This is
a sign of an increasing awareness of the fact that the conception of omnipotence,
which included the idea of eternal alternatives, was very different from philosophical
modalities, and there were some twelfth-century attempts to explicate the idea
of synchronic alternatives more systematically.
In addition to the doctrines of omnipotence and eternal choice between providential
options, divine modalities were discussed in treating the compatibility of
divine omniscience and the contingency of events in the created world. In his
longer commentary on De interpretatione, Boethius says of God that ‘he knows
future events as happening contingently and not necessarily so that he does not
ignore the possibility that something else might take place.’ 39 In his later work
Consolation of Philosophy, Boethius argues that God is atemporal and has timeless
knowledge of everything. God’s timelessness involves his having the whole history
present to him simultaneously. God’s knowledge is not foreknowledge, since it is
not temporally located, but the predictions of future contingents are true or false
from the point of view of God’s eternal knowledge of the things referred to. It
is necessary that if God knows that p, then p. This ‘conditional necessity’ does
not imply the ‘simple necessity’ of p. 40 This approach was very influential and
was further developed in Aquinas’s theory of God who grasps all combinations of
things at particular times by one eternal vision. God has an immediate knowledge
of all things and their relative temporal order, though none of them is past
or future with respect to His cognition. The objects of divine omniscience are
necessary by supposition (i.e., with respect to God’s knowledge and providential
plan), but many of them are contingent with respect to their proximate causes. 41
God’s eternal and immutable vision includes the knowledge of things which are
future contingents in the temporal order, and he can supranaturally inform lower
intellects about these things – otherwise there could not be true prophetic predic-
(Grottaferrata: Collegium S. Bonaventurae ad Claras Aquas, 1971-81), II.18.5-6; Simon of Tournai,
Disputationes, ed. J. Warichez, Spicilegium Sacrum Lovaniense, Études et Documents 12
(Louvain: Spicilegium Sacrum Lovaniense,1932), 35.2 (104.32-105.29); Peter of Poitiers, Sententiae,
I.7 (65.444-66.452, 67.498-68.502); Alan of Lille, Regulae caelestis iuris, ed. N.M. Häring,
Archives d’histoire doctrinale et littéraire du moyen âge 78 (1981), 164-5. This was the background
of the scholastic doctrine of God’s absolute and ordained power. For similar discussions
in medieval Arabic thought, see Kukkonen 2000.
38William of Auxerre, Summa aurea, ed. J. Ribaillier, Spicilegium Bonaventurianum 16-20
(Paris: Editions du CNRS and Rome: Collegium S. Bonaventurae ad Claras Aquas, 1980-86),
I.11.2 (206-9).
39In Periherm. II, 226.9-12.
40Philosophiae consolatio, ed. L. Bieler, Corpus Christianorum Series Latina 94 (Turnhout:
Brepols, 1957), V.6, 25-32; cf. Augustine, De civitate Dei XI.21. Boethius’s conception of God’s
atemporal knowledge is meant to explain how future contingent events retain their indeterminateness
while being certainly known as atemporally present. See also J. Marenbon, Boethius
(New York: Oxford University Press, 2003), 123-45.
41Scriptum super libros Sententiarum, I.38.1.4-5; Summa contra gentiles, I.66-7; Quaestiones
disputatae I: De veritate, 2.12; In Peri herm. I.14, 194-6; Summa theologiae I.14.13.