Al-Ghazali was an avowed determinist, and in his work on cosmology, he teaches that God not only determines everything, but is the only efficient cause there is. Nonetheless, Al-Ghazali does seem to use the language of causality of objects and processes in the temporal realm as well. With each effect traced to its efficient cause, it would lead back, eventually to a primordial first act of God, who alone is in charge of making causes function as causes. Al-Ghazali appropriates Avicenna's understanding of creation, arguing that
""being" is passed down from God to the first and ontologically highest creation and from there in a chain of secondary efficient causes to all other existents. It is important to acknowledge, however, that God is the only true efficient cause...in this chain. He is the only "agent," all other beings are merely employed in his service"(Griffel, 2013).
Like Avicenna, furthermore, Al-Ghazali held to the belief that this world is the best of all possible worlds; a theological position which anticipates that one set forth by Leibniz. He differs from Avicenna, however, in that he believed that God chooses between alternatives rather than his will being determined by his essence.
Al-Ghazali's motive in setting forth God's nature as the only true, efficient cause was to safeguard the doctrine of predestination, as a Sunni Muslim, over and against the Mu’tazilites and Shiites.Humans have no free will, and their impression of having such a choice is merely an illusion. He follows Avicenna's determinism in arguing that everything in the world is contingent in one sense yet also necessitated by something else in another sense (Griffel, 2013). For both Avicenna and Al-Ghazali, God's will makes all events and entities necessary.
Al-Ghazali does, however, take an innovative twist when it comes to his articulation of the traditional Ash'arite understanding of predestination, as we will now see (Griffel, 2013). Al-Ghazali was a member of the Ash'arite school of Islam, founded by Al-Ash'ari. The latter rejected the idea that entities had distinct natures, as well as the idea that real causal connections existed in the spatiotemporal realm.
This would later come to be known as the doctrine of occasionalism. For Al-Ash'ari, all of reality consisted merely of "accidents," which carry atoms that lack attributes and function merely to make up the shapes of individuals. Atoms in our spatially extended bodies are distinct substances. Our thoughts are "accidents" which are constituted by atoms in our brain. Even faith in God is an accident, though it is constituted, he believed, by the atoms that make up the human heeart.
These accidents cannot subsist from one moment to the next on their own, and instead require God to assign the accidents an individual's body, only to create a whole new set of accidents from one moment to the next. These subsequently existing accidents are causally independent of the ones which they have replaced. Although our attributes appear to endure, they are really the result of God replacing our previously existing accidental atoms with identical ones from one moment to the next. This is how he understood the nature of movement as well. The atoms of entities are created afresh from one moment to another a distance from the previously existing set. Every single moment, God creates an entirely different world out of a new set of atoms.
Al-Ghazali's approach to causality was less extreme than this form of occasionalsim. Influenced by Avicenna's understanding of secondary causes, God uses certain creations as means of mediating secondary causes by creating a "series of efficient causes where any superior element causes the existence of an inferior one"(Griffel, 2013). Like Aquinas and Aristotle, Avicenna denied that there could be an infinite regression of causes, thus proving the existence of God as the Prime Mover. A series of causes and effects has three components:
1) First element - the only real cause in the chain.
2) Middle element - one or more intermediaries through which the ultimate or last effect of the chain is produced.
3) Last/Ultimate element
Though perhaps an occasionalist of a sort, Al-Ghazali does not deny the existence of secondary causes the way Al-Ash'ari before him had done. He merely denies that the connection between a secondary cause and its effect are necessary. We tend to habitually believe that the spatiotemporal contiguity of an apparent cause and an apparent effect means that the one is necessitated by the other, but this is not true. It is God's will which has caused them to co-incide with one another, rather than the effect necessarily following from the cause in and of itself. There are thus four conditions which our understanding of causality must fulfill, for Al-Ghazali:
1) Cause and effect may possess a connection, but not a necessary one.
2) This effect can come about by any other cause.
3) God causes two events side by side. This in particular is clearly compatible with Avicenna's understanding of causality, according to which spatiotemporal contiguity is the means by which a secondary cause leads to an effect.
4) God's creative powers follow an antecedent decision concerning what will happen.
Thus, Al-Ghazali is not quite a straightforward occasionalist, only suggesting at times in his 17th discussion in his Incoherence of the Philosophers that occasionalism may be a potential (though not a necessary) solution.
"It is important to understand that [he] does not deny the existence of a connection between a cause and its effect; rather he denies the necessary character of this connection. In the First Position of the 1th discussion [he] brings the argument that observation cannot prove causal connections. Observations can only conclude that the cause and its effect occur concomitantly"(Griffel, 2013).
Thus, while he accepts the possibility that in at least some cases an effect follows from a secondary cause, he disputes Avicenna's position that effects follow necessarily from secondary causes by virtue of what obtains necessarily in the relation between the cause and effect itself. He thus "attacks Avicenna's necessitarian ontology not his secondary causality. The dispute between [him] and Avicenna is not about causality as such, rather about the necessary nature of God's creation"(Griffel, 2013).
Indeed, if we are to understand the debate between Al-Ghazali and Avicenna, we must understand not merely differences in nomology, but in modality.
"Kukkonen (2000) and Dutton (2001) have shown that the two start with quite different assumptions about necessity. Avicenna's view of the modalities follows the statistical model of Aristotle and connects the possibility of a thing to its temporal actuality (Bäck 1992). A temporally unqualified sentence like, “Fire causes cotton to combust,” contains implicitly or explicitly a reference to the time of utterance as part of its meaning. If this sentence is true whenever uttered, it is necessarily true. If its truth-value can change in the course of time, it is possible. If such a sentence is false whenever uttered, it is impossible (Hintikka 1973, 63–72, 84–6, 103–5, 149–53). In Aristotelian modal theories, modal terms were taken to refer to the one and only historical world of ours. For Avicenna, fire necessarily causes cotton to combust because the sentence “Fire causes cotton to combust,” was, is, and will always be true"(Griffel, 2013).
Griffel, Frank, "Al-Ghazali", The Stanford Encyclopedia of Philosophy (Summer 2013 Edition), Edward N. Zalta (ed.), URL = <plato.stanford.edu/archives/sum2013/entries/al-ghazali/>.