The second family of arguments originally grew out of heated debates about whether the world has a beginning (and an end) in time. Many medievals accepted Aristotle’s causal apparatus, but considered the view that the world is eternal, prevalent in ancient Greek thought, as at least problematic, and would find the related idea that matter is eternal at odds with the doctrine of creation ex nihilo. A key role in the history of arguments for creation is played by Alexandrian Christian John Philoponus (c. 490-570s) and his works Contra Proclum and Contra Aristotelem. In the latter work, now extant only in fragments, Philoponus argues against the eternity of the world (including the supralunar realm) by attacking Aristotle’s Physics arguments for the eternity of time and motion.
In Physics 8, Aristotle had argued that it is impossible that there was ever a first motion, since every motion is the actualization of a preexisting potentiality. On the assumption of a first motion, one must admit the existence of a thing, which, prior to the first motion, has the potentiality of being in motion. The thing in question must either have been there always, in a state of rest, or it must have come into existence at some prior point. Now if it was at rest, there must according to Aristotle have been a cause for its state of rest, and if it came to be, there must have been a cause for its becoming. In any case, there is motion before the first motion; hence, the initial assumption of the existence of a first motion must be abandoned, and the series of motions must be eternal. Since time, moreover, is either a motion itself or a measure of motion, time too is eternal.
In his Contra Aristotelem, Philoponus argues that Aristotle’s argument, if valid, would be a refutation not only of creation ex nihilo, but also of that eternal motion which Aristotle himself thought the heavens were engaged in. Since in eternal motion there is no preceding potentiality for motion, Aristotle’s definition of motion as the actualization of the movable qua movable cannot be valid.
Philoponus puts forward a series of further counterarguments, which trade on the theoretical unmanageability of infinities. Exploring the Aristotelian notion of the transmutation of the four (sublunar) elements of one into another, Philoponus argues that any given now existing element must be the outcome of a finite number of transformations, since an infinite series cannot be traversed. A second argument appeals to the impossibility of adding to an infinite: if current motions increase the total number of motions completed, then the past number of motions cannot be infinite, since an infinity cannot be increased. A third, similar, argument rests on the premise that an infinite cannot be multiplied. If the sphere of Saturn has completed an infinite number of revolutions, and the sphere of the planet Jupiter, for example, rotates roughly three times faster, then the number of Jupiter’s revolutions should be three times infinity, which is absurd.
Similar arguments, appealing to the impossibility of adding to and multiplying infinities, can be found among the Islamic scholastics of the kalam tradition, and it has been argued that Philoponus was the ultimate source of these (Davidson 1969, 1987). Unlike Philoponus himself, and unlike later Arabic philosophers and Christian scholastics, who espoused various forms of hylomorphism, the majority of writers of the Mu'tazilite and Ash'arite schools advocated a form of atomism, the so-called doctrine of accidents. The universe consists of featureless atoms, arranged into bodies or beings, the characteristics of which, such as composition and movement, are all mere accidents as opposed to being somehow dependent on internal structure, nature, or essence. According to what became the standard kalam proof of creation, the accidents, which are present in bodies, are subject to destruction and must, therefore, have been generated. Further, bodies cannot be free of accidents, and in particular not precede them. Now since the accidents are generated, so too must the very bodies be, and since the universe consists of only bodies and accidents, the world as a whole must have been generated.
Al-Farabi and Avicenna rejected the kalam arguments for creation in time and maintained that the universe is eternal. Al-FarabI also read Philoponus firsthand, and attacked him in at least four of his works. Instead of arguments for God based on arguments for creation, al-Farabl appropriated the Aristotelian arguments in the Physics and the Metaphysics for a first mover (Hammond 1947:18-22). In these arguments, Aristotle appeals to the impossibility of an infinite regress of movers, and so these latter arguments appear prima facie at odds with Aristotle’s argument for there not being any first motion. According to Averroes and Maimonides, al-FarabI set out to answer this problem in his work On Changeable Beings, now lost. In it al-FarabI reportedly argued that although there is no first motion, and the series of motions is infinite, the motions or objects involved do not exist together, or simultaneously, and so do not taken together constitute an actual infinite. Moreover, while time is in a sense an infinite magnitude, it is neither a spatial, nor an ‘‘actual’’ magnitude.
Avicenna put forward an argument for the existence of God based on the distinction between what is possible of existence and what is necessary of existence. The distinction itself constitutes a challenge to the Aristotelian statistical (temporal-frequency) interpretation of possibility and necessity. While in the Aristotelian picture eternal things tend to be viewed as necessary since they exist at all times, Avicenna operated with a causal interpretation of modalities where a possible is a thing that requires a cause for its existence (be the thing eternal or not) and a necessary is that which is uncaused. Through an a priori examination of the concept of existence, Avicenna aims to prove the existence of a being necessary in the sense of uncaused, a being he identifies with God. Each existing thing is either possible or necessary, and since what is sought is the necessary, the most important step in the proof is showing that the existence of an arbitrary possible entails the existence of the necessary. Any chain of causes and effects made up solely of possibles, regardless of whether it is finite or infinite, must terminate in a cause which is not itself an effect, that is, in a necessary. The total aggregate of possibles as a whole cannot be otherwise than itself a possible, and so per definition it requires a cause. In his Third Way, Aquinas argues in a similar way from the existence of contingent things. While Aquinas presents his argument as relying on sensory experience, however, Avicenna explicitly claims his proof does not rely on experience, but solely on the nature of existence (Marmura 1980: 339).
Both (Gazall and Maimonides took a more complex stance vis-a-vis the question whether the world had a beginning in time. In his Incoherence of the Philosophers, (Gazall puts forward Philoponus’ arguments against eternity from the impossibility to multiply and add to infinities with the aim of showing that the kalam arguments for creation, although these too associated with serious problems, are at least as rationally defensible as the arguments of Avicenna and Aristotle. Maimonides thinks the claim of the world’s eternity has neither been proved by Aristotle nor disproved by the kalam, and argues in the second book of his Guide of the Perplexed that the existence of God as a first mover can be shown to follow from 26 premises, 25 of which he considers self-evident or easily provable. The 26th premise, stating the world is eternal, Maimonides claims to be ‘‘possible,’’ and grants for the sake of argument.
While Bonaventure considered [1] Philoponus’ arguments valid, and [2] as established the claim that the world had a beginning in time (Sentences 2, dist. 1, p. 1, art. 1, q. 2), Aquinas held, at the time of writing ST, that the world’s eternity can be neither proved nor disproved. Aquinas’ arguments for a first mover and a first efficient cause, the first and second of his ‘‘ways,’’ should therefore be seen as neutral with respect to this issue. By employing the distinction between causes essentially and merely accidentally required for a given effect, he argues, following Avicenna and Averroes, that only series of accidental efficient causes can proceed back to infinity (ST I, 46, art 2, ad 7). Consequently, Aquinas’ first and second ways concern essential, or per se causes.
Like Aquinas, Scotus thinks very carefully about the status of his arguments, but unlike Aquinas, he presents his argument for the existence of God as a proof proper, as an Aristotelian demonstration, as a series of deductions from premises necessary, certain and self-evident. In his view, a demonstration propter quid (of the ‘‘reasoned’’ fact) of God’s existence is not possible to construct, but a demonstration quia (of the bare fact) is.
In his very complex proof, Scotus begins by establishing that there exists in actuality a first entity in three different orders of things: the order of efficient causes, the order of ends or final causes, and the order of eminence or excellence. A key role in the arguments is played by the notion of an essentially ordered series of beings with respect to causality. In such a series, at each element pair, (1) the causes involved are contemporaneous, (2) a cause depends on the prior cause in the series for its own causality, and (3) the prior cause is more perfect, more eminent, than the posterior. Such a series cannot be infinite, according to Scotus, since without a first cause, the series as a whole would be uncaused. Scotus then argues that three primacies — that of being a first cause, an ultimate end, and the most excellent being — are properties of one and the same being, and that this first being is intelligent and endowed with will. Finally, he argues the first being is infinite.
World History
