This is the condensed and slightly modified version of a paper I wrote last semester. Longstanding in the great monotheistic traditions of Christianity, Judaism, and Islam has been a popular argument for the existence of God known today as the “cosmological argument.” Its current expounder-in-chief among Christians, William Lane Craig, has adapted a version of the argument derived from the Kalam tradition of Muslim scholarship. Similar arguments were advanced by Thomas Aquinas in the Middle Ages and can even be seen in some Hellenistic Jewish literature among a variety of other sources from ancient times to present day. The arguments for the most part take their starting point in the writings of Aristotle and in particular the argument laid out in Metaphysics XII concerning an “unmoved mover.” Yet there are some significant differences between Aristotle’s original argument and contemporary manifestations of the cosmological argument.
Aristotle’s cosmological argument occurs amidst discussions of substance and causation, and that context is extremely important to understanding the argument. Substance for Aristotle is what “certain thinkers assert to be capable of existing apart” (1069ab). Aristotle’s argument can be understood as a critique of the Platonic notion of the Forms. Essentially, Aristotle’s argument is that the principles which cause change in individual substances- by which he seems to mean “formal change,” i.e., the things which demarcate individual substances as being a particular thing, whether they be shape or color or size or texture or movement or any other such factor- only exist as they are actualized in the particular things. Thus, Aristotle seems to say, we can note ways in which these causes are analogous between one another, but we cannot make the conclusion, as Plato attempts to do, that such causes exist as universal Forms that stand apart.
Aristotle begins his argument by asserting that movement must have always existed, and if this is the case then time must have always existed and likewise space (1071b). From this starting point he argues that substances must have always existed because without them this movement could not have existed (1071b). Further, he argues as another critique of the Platonic notion of the eternal Forms, these eternal substances cannot exist in a state of potentiality but must be actualized for motion to exist. The most significant point of this argument is that substances must be eternal.
In an interesting turn, then, Aristotle next adopts one of the key components of his teacher Plato’s ideology, namely that the moving, changing, actualized world is somehow less real than the stable, unmoving, eternal world. Based on this idea he will conclude that while moving objects exist eternally, they exist only in an intermediate state. What is really needed is an unmoving object to ground everything, and what this object must be is eternal, actual, and most importantly a substance (1072a). This Platonic idea that the ultimate cause needs to be free from the vagaries of motion or change is important for understanding the conclusion of this argument, a conclusion which has had profound implications on much of later theology. This leads to the final conclusion of Aristotle:
It is clear then from what has been said that there is a substance which is eternal and unmovable and separate from sensible things. It has been shown also that this substance cannot have any magnitude, but is without parts and indivisible. But it has also been shown that it is impassive and unalterable; for all the other changes are posterior to change of place. 1073a
This substance is the famous “unmoved mover” who is eternal and separate. From this will be derived many of the classical ideas about God in the monotheistic traditions: that God is eternal, transcendent and distinct from the world, indivisible, unchanging, etc. This cosmological argument, we might claim, is not simply significant for its apologetic value but also because of the way it shapes the theological tradition.
In stark contrast to some more contemporary cosmological arguments, such as that advanced by William Lane Craig, which hold that the universe has a definite temporal starting point of which the “unmoved mover” is the first cause, Aristotle maintains that motion has eternally existed as we have discussed above. How, then, is the “unmoved mover” a “first cause”? The answer, I believe, lies in this discussion of substance. For Aristotle substance is what underlies matter to allow it to take its form. What I believe this argument establishes is essentially a hierarchy of substances. This is Aristotle’s twist on Plato’s notion of the Forms existing as a hierarchy. Since Aristotle denies that merely potential Forms can exist, he insists on the actuality of all substances. The substances underlie matter and allow motion to exist. What underlies the individual substances, however, and allows them to exist? Other substances, in a kind of genetic tree or in a kind of motion of their own. Aristotle thus thinks he has solved the problem of the universe’s existence (NB: not its origin, because it has always existed) by the idea of underlying substances tracing back to a “first,” or perhaps better put “primary” or “foundational” substance, the first cause or “unmoved mover,” which exists eternally and apart from other substances but whose existence gives rise to the existence of the other substances.
Whether or not Aristotle’s argument ultimately works or convinces us that there is such an “unmoved mover,” what I think Aristotle does establish is an alternative type of causation to what we typically think of today. We can call this more familiar type of causation, which underlies the Kalam argument, “temporal causation.” It has to do with the sequence of cause-and-effect stretching back through time. The Kalam argument maintains that there must be a definitive starting point to this sequence of “temporal causation.” The alternative type of causation that Aristotle has presented we can call “ontological causation,” having to do with a hierarchy of substances from which others are derived ontologically but not necessarily temporally. Interestingly, while I think Aquinas followed Aristotle’s notions of causation here fairly closely, for the most part the Christian tradition of philosophical theology has not employed this notion to particularly great affect (at least not the Protestant tradition). I think the potential implications of this distinction, though, are fairly significant, especially as regards discussions about human agency/free-will and divine causation.