 |
 |
 |
 |
|
 |
 |
|
 |
The effect of an ongoing increased focus on Aristotle was that some philoso-
phers were moving in the direction of a naturalistic account of the soul, forging
ahead into more experiential and scientific theorizing that was divorced from
religious belief. The ensuing conflict between naturalistic and religious
approaches to the soul led to the formation, in the 1260s, of the “double-truth”
theory of the relation between reason and faith, according to which philosophy
and religion should pursue truth independently of each other in spite of appar-
ent conflicts in what they might find. This theory affected all of late Scholastic,
as well as Renaissance thought, and
foreshadowed the more radical divorce
between science and religion that would begin in the seventeenth century.
A case in point is Siger of Brabant (1240-1284), whose book I n Tertium de
Anima was completed around 1269 and posed a challenge to the doctrine of per-
sonal immortality. Although Siger borrowed from several of the Scholastics who
preceded him, he was more of a disciple of Averroës than he was a follower of
any of them. In his view, each human has a vegetative and sensitive soul that is
biologically transmitted; however, the rational soul (the “intellective soul”),
which is neither rooted in the vegetative and sensitive souls nor has any vegeta-
tive and sensitive functions, is not biologically transmitted but comes “from
without” and is the same in every human. When the rational soul makes its pres-
ence felt in a particular human, it does not corrupt the vegetative and sensitive
souls but unites with them. However, what results is not “one simple soul” but a
“composite soul.”
17
This composite soul is not a compound of matter and form but of hierarchi-
cally arranged forms, with those that are lower in the hierarchy acting as a kind
of “matter” to those that are above. The rational soul is not the substantial form
of the body but rather its perfection. It perfects the body not through its sub-
stance but through its power, which is responsible for human understanding.
Siger thus emphasized the operational, rather than the substantial, relation of
the rational soul to the human body. Aquinas, by contrast, argued that if this
view were true, it would be impossible to show that a single individual under-
stands. For a person’s understanding would not be his but only that of the intel-
lect
that uses his body. “The action of a part,”
Aquinas concluded, “is the action
of the whole only when the whole is one being.”
18
On the question of immortality, Siger adopted Averroës’ interpretation of
Aristotle’s view of the rational soul, or agent intellect, according to which it must
be free of matter in order to perform its function, and if free of matter, it cannot
be individuated. As a consequence, he claimed, the rational soul is unavailable as