“What then of Ockham? He supposes that the conservation of all things in being shows that a first efficient cause exists, but he does not consider that the demonstration from efficient causality works. For Ockham, it is possible that in a multitude of things, there are enough sources of actualization that one transcendent ‘first mover’ is not needed. In my view, this conclusion rests on failing to appreciate adequately the contingency of all finite things. After all, any accidentally ordered series of finite causes depends on an essentially ordered series in order to exist. Even if the finite causes in an accidentally ordered series are infinite in number (as Aquinas grants), they cannot account for the existence of the series, since the existence of the infinite series would itself be dependent and in need of a cause. With regard to whether natural reason can prove God’s unity, the question here is again Aristotelian: Can there be more than one Pure Act? Ockham argues that we can answer in the negative only on the basis of faith, not on the basis of reason. His reasoning, however, relies on his view that all spiritual substances – God, the angels, and spiritual souls – are equally simple. In denying that angels and spiritual souls, whose being is not their essence, are composite in a way that God is not, Ockham overlooks the unique simplicity of Pure Act. When we demonstrate the existence of pure actuality (a first cause, unmoved mover, source of all things), we demonstrate the existence of something whose being and power are absolutely simple, infinite, unlimited, and unrestricted. In this respect, Ockham would have been aided by a deeper attention to the patristic tradition.
Even Ockham, however, holds that we can demonstrate the existence of God on the basis of the conservation of all things in being. The common thread of this first chapter is thus not completely absent even in Ockham. But since Ockham’s demonstration of God’s existence from conservation does not include God’s unity, the argument from conservation has not yet demonstrated the existence of the true God (who is one). Indeed, with respect to causality, act/potency, and simplicity, Ockham’s Aristotelianism lacks some crucial elements that we find in John of Damascus and Aquinas, no doubt in part because Ockham largely excludes Neoplatonic insights. His work therefore foreshadows the broad Reformation and Enlightenment movement away from Aristotelian and Neoplatonic demonstrations of God’s existence.”
– Matthew Levering, Proofs of God –
– Lucas G. Westman