The “existential inertia” thesis holds that, once in existence, the natural world tends to remain in existence without need of a divine conserving cause. Critics of the doctrine of divine conservation often allege that its defenders have not provided arguments in favor of it and against the rival doctrine of existential inertia. But in fact, when properly understood, the traditional theistic arguments summed up in Aquinas’s Five Ways can themselves be seen to be (or at least to imply) arguments against existential inertia and in favor of divine conservation. Moreover, they are challenging arguments, to which defenders of the existential inertia thesis have yet seriously to respond.
The article is a supplement of sorts to the discussion of the Five Ways contained in chapter 3 of Aquinas. It sets out the arguments in a more formal manner and is concerned less with Aquinas’s own way of stating them than with the way they have been developed and refined within the broader Thomistic tradition down to the present day. As the abstract indicates, the paper is particularly concerned to show how each of the Five Ways – or rather, how each of the general patterns of argument that the Five Ways represent – when followed out consistently implies that the world could not in principle continue for an instant without the conserving action of God. In the course of defending this claim the paper also responds to the contrary arguments of writers like Mortimer Adler, John Beaudoin, J. L. Mackie, and Bede Rundle.