On Avicenna’s analysis, there are efficient causes that act on a patient. Here, he closely follows Aristotle’s own analysis: an efficient cause activates some potentiality in a patient, thus changing said patient. The agent is prior to the effect in some way. The patient goes from being one way to being another way. The change—the activation of the
potentiality—is wrought by the efficient cause’s action. Such efficient causes can be
natural—that is, agents that act by nature—or they can be volitional—that is, agents that act by will. So, efficient cause C is the cause of some change in patient P if C is in some way prior to P and some action of C brings about change in to P.
There exists another type of efficient cause that does not act upon a preexisting patient but still produces something new: in this circumstance, the change is the existence of something new, something that comes to be as a result of the agent’s action. The agent still must be prior to its effect in some way, but there is no patient that underlies this change: the agent does not necessarily act upon something to bring about said change. This metaphysical efficient cause M is the cause of some thing O if M produces O ex nihilo.
Avicenna adds another layer, so to speak, to his robust explanation of efficient causation by arguing that metaphysical efficient causation includes both the production of something new and the sustenance of something. A builder is an efficient cause of a building but is not, strictly speaking, the metaphysical efficient cause because he is not responsible for
the preservation of that building’s existence. A metaphysical efficient cause M is the cause of some thing O if M produces O and M sustains the existence of O in some way. Avicenna believes that any production ex nihilo involves the agent sustaining the new substance.
Coupled with Avicenna’s lengthy treatment of Aristotelian efficient causation is his general endorsement of Neoplatonic emanation as a manner of causation. God emanates, producing the First Intellect by an act in accordance with its will. God is bound it emanate only one simple thing, and each intellect emanates as well, and, it seems likely that those intellects emanate in accordance with their wills.523 So far, then, it seems that agent A emanates B when A wills to emanate. It seems incorrect to argue that agent A emanates B when A wills to emanate B because Avicenna does not specify that the later Intellects intend to emanate precisely the thing they produce. In God’s case, it seems likely that God
emanated the First Intellect because God intended to emanate the First Intellect specifically, but for the other Intellects, it seems that they intended to emanate something as a
component of their larger intention to be as like God as possible. What remains unclear is whether there are emanations that are produced by nature instead of by will. As noted, Avicenna asserts that the Intellects will their celestial spheres to move in a circular manner, but it is not clear that everything they do is volitional.524 In the case of voluntary emanation, an agent E emanates effect I if E wills to bring about the existence of I and initiates an emanation that, directly or indirectly results in the existence of I. E’s volition must be congruent with E’s nature or essence. In the case of natural emanation, which may be a theoretical type of causation, agent E emanates effect I if E has a nature that invariably leads
523 Avicenna, Metaphysica, p. 88-9.
524 Avicenna, Metaphysica p.88-9
(at least in certain circumstances) to the existence of I and initiates an emanation that, directly or indirectly, results in the existence of I.525
2. Aquinas
On Aquinas’s analysis, efficient causation is the type of causation wherein some agent acts. The focus of Aquinas’s analysis of efficient causation is the action performed by the agent. Accordingly, there are at least two general classes of efficient causation: instances in which the agent acts upon some patient and instances in which the agent does not act upon some agent. An efficient cause, in actualizing some potentiality in the patient, affects a change in either the accidental or substantial form of its patient.526 An efficient cause E is the cause of some change in patient P if E is in some way prior to P and some action of E brings about some change in P.
Aquinas discusses efficient causes as causes that conserve or sustain their effects.
Like Avicenna, he asserts that some efficient causes both produce or alter some effect and are responsible for the continued existence of that effect. An efficient cause E is the cause of the continued existence in patient P if E is in some way prior to P and some action of E sustains the existence of P. In this type of efficient causation, the central focus for Aquinas is still the action of the agent—which, Aquinas argues, is some continuation of the action by which God produces things ex nihilo.527
Since action is the primary indicator of an efficient cause—an efficient cause must act in order to bring about some change—Aquinas is able to explain how an efficient cause could act without a patient. The analysis of this type of efficient causation depends entirely
525 I do not include Taylor’s transcendently necessary type of emanation as a potential type of emanation because it does not occur in Avicenna’s writings.
526 Aquinas, De Principiis Naturae 1-3.
527 Aquinas, ST Ia.104.1 resp 1.
upon the agent’s action. An efficient cause E is the cause of P if E is in some way prior to P and some action of E brings about P. A further complication is that for Aquinas, there can be only one efficient cause who acts without a patient: God. As a fully actualized being, God has the ability to produce new being without any patient to underlie that production. So, more strictly, the efficient cause G is the cause of P if G is in some way prior to P and some action of G brings about P. If creation is understood passively, the formulation would be that the efficient cause G is the cause of P if G is in some way prior to P and P depends on G for its existence.
When specifying precisely what emanation is like in terms of creating, it is important to note that Aquinas differs from Avicenna by denying that any intermediaries are
productive of new being from nothing. Aquinas must offer a different analysis of voluntary emanation. Aquinas’s analysis would instead be that agent E produces effect I if E wills to bring about the existence of I (a volition that must be congruent with E’s nature or essence) and initiates an emanation that directly results in the existence of I. Because only God can emanate entirely new being, Aquinas’s understanding of emanation in creating could be articulated as an G producing effect I if G wills to bring about the existence of I (a volition that must be congruent with G’s nature or essence) and initiates an emanation that directly results in the existence of I.
While Avicenna’s approach to natural emanation may be merely theoretical, Aquinas outlines cases of natural emanation, both cases in which God produces a natural emanation and in which other agents do so. It is difficult to lay out divine natural emanation in similar terms to voluntary emanation, however, because what is emanated by God are the persons in the Trinity. What God emanates is, strictly speaking, also God. So, it is tempting to initially
posit that in natural emanation, agent E produces effect I if E has a nature that invariably leads to the existence of I and initiates an emanation that directly results in the existence of I.
But this proposal must be modified to apply to the Trinity, given the relation between God the Father, God the Son, and God the Holy Spirit. One such attempt might be to say that agent GF generates GS if GF has a nature that invariably leads to the generation of GS and GF exists. This attempt accurately emphasizes the close connection between God’s essence and God’s existence as a Trinitarian being.
Let us apply this analysis to at least one other case of natural emanation, namely the sun emanating light. The sun emanates light if the sun has a nature that invariably leads to the generation of light and if the sun exists. However, this analysis glosses over the need for the sun to exist in the sort of environment in which it is able to produce light; this may be oversimplifying the physical processes needed in order for the sun to actually produce light.
The difference between God and the sun is that the sun depends upon certain circumstances other than its existence to produce light. So, a better analysis for the sun would be that the sun produces light if the sun has a nature that invariably leads to the existence of light in certain circumstances, the sun exists, and those circumstances are met. The sun fulfilling its nature, as it were, requires more than the brute existence of the sun. So, for natural
emanations produced by beings other than God, agent E produces effect I if E has a nature that invariably leads to the existence of I in certain circumstances, has those circumstances met, and initiates an emanation that directly results in the existence of I.