plunging into describing the levels of emanation that make up the cosmos, he
builds a foundation of systematic definitions and proofs. In other words, he
integrates Neoplatonism around the problems bequeathed by kalam: the nature
of substance and attributes, proofs of God and the creation of the world.
To begin at the beginning, Ibn Sina holds, is to study being, the most
fundamental of all concepts. He proves this with an argument that foreshadows
Descartes’s cogito but is used for a different purpose. Imagine a man flying in
a dark and completely empty space; though he would know nothing of sensory
qualities or material bodies, he would unquestionably know that he exists.^17
When the senses are restored, these would show only further modifications of
being.
Although there is no other notion prior to being, it admits distinctions. The
mind can think of what something is—its essence or “whatness” (as the
Christian scholastics would say, its quiddity)—without its actually existing,
and even without its possibly ever existing. Existence is thus superadded to
essence, making up the two fundamental aspects of being. This distinction was
an old one, found in Aristotelean logic. But Ibn Sina does not merely leave his
distinctions within a logical treatise; in his al-Shifa he elevates them to meta-
physical principles as the foundation of an ontological system (Afnan, 1958:
115–130; Davidson, 1987: 281–310; Hyman and Walsh, 1983: 241–255).
Within existence, Ibn Sina adds the further distinction between necessary
being—that of which to assume its non-existence would lead to an impossibil-
ity—and non-necessary being. Ibn Sina criticizes the theologians and logicians
for failing to make adequate distinctions; they define “necessary” and “possi-
ble” in a circle, in terms of each other. Ibn Sina argues that there is a further
category, the contingent: that which is neither necessary nor impossible. Thus
we can conceive of (1) being which is necessary of itself, and (2) being which
is merely possible in itself but necessary as the result of some external cause.
If a being were necessary purely of itself alone, it could contain no internal
distinctions; it would have to be unified, simple, and incorporeal: in short, it
would be God. Does such a being exist? Ibn Sina notes that since we know
something does exist, it must be of either type (1) or type (2). If it is the former,
the proof is complete. If it is the latter, it must depend on a separate being to
maintain it in existence; and that can only be (1). A being with all the
characteristics of God must accordingly exist; and the rest of the world can be
logically derived from it.
If Ibn Sina reaches a high level of abstraction, it is because he builds on
the whole preceding Islamic intellectual community. The central problems that
he sets for himself—to delineate the attributes of God; to show how the world
was created; to demonstrate the different components of what we call causal-
ity—were those around which Muslim rational theologians had traded accu-
Tensions of Ideas: Islam, Judaism, Christendom^ •^419