The Neoplatonists, who developed as a pagan rival to Christianity, eventually
produced a full-fledged religious conception of God; but since their synthesis
included Aristoteleanism, the One is very unlike a creator or Providence. Philo-
sophical arguments over God finally became focused when the Neoplatonists had
to make their peace with victorious Christianity. The Patristic writers were content
with the argument from design—the order of the world implies a creator—but as
Averroës later said, this is an argument for laypeople, not one argued at the level
of formal philosophical consideration (Davidson, 1987: 219, 236). The more
sophisticated level emerged with Proclus (mid-400s), the last gasp of the pagan
Neoplatonist school at Athens. He was the first to recognize that Aristotle’s proof
of an unmoved mover from the motion of the spheres is not a proof of a cause of
the existence of the spheres; Proclus added an argument that the existence of the
heavens requires an eternal being to sustain their existence, and compiled 18 proofs
for the eternity of the world (Davidson, 1987: 51, 281–282). Proclus’ pupil was
Ammonius (304 in Figure 3.8), who abandoned Neoplatonism for Christianity; he
was the teacher of both Simplicius (306 in Figure 3.8) and John Philoponus.
Simplicius was the first to take the impossibility of an infinite regress of causes as
a proof of God (Davidson, 1987: 338). And Philoponus based his arguments
explicitly on a refutation of Proclus (Contra Proclum); in converting to Christian-
ity, he reconverted the cultural capital of his school into a reasoned philosophical
theology which Christianity had previously lacked. With the ending of his lineage,
however, Philoponus’ arguments were not taken up in Christian philosophy. They
survived largely because similar lines of argument emerged among Muslim theo-
logians. Less particularistically, the ancient struggle between an anthropomorphic
monotheism and a defensive religion of philosophical syncretism (i.e., Christianity
versus Neoplatonism) eventually brought about reasoned arguments over the fun-
damental items of the religious cosmology; and these arguments were picked up
again when another monotheistic anthropomorphism (Islam) developed its own
intellectual networks.
- Davidson (1987: 214–215, 309–310), however points out that Ibn Sina did not
produce a pure ontological proof, based on concepts alone, as Anselm did in
Europe two generations later. Ibn Sina included reference to the fact that something
exists. But he raised philosophical analysis toward the ontological level, although
most of the further development was to take place after his texts were transmitted
into Christian philosophy.
- As compared to Descartes, Ibn Sina did not lay stress on the existence of self in
the “cogito ergo sum,” but emphasized instead the modality of being which is
thereby revealed.
- Ibn Sina is the high point of Islamic logic; he contributes a theory of categorical
propositions involving quantification of the predicate; of hypothetical and disjunc-
tive propositions; of singular propositions; and a theory of definition and classifica-
tion (Rescher, 1964: 154–155). A rather sterile debate between proponents of Ibn
Sina’s “eastern” logic and the “western” logic of the Baghdad and Cairo schools
supplied what focus of attention there was within intellectual life from the mid-
1100s down through the mid-1300s.
Notes to Pages 414–423^ •^985
