One of the goals of Apologetics is to deal with the objections that people have regarding the existence of God. Over the next several weeks, we will be listing some of these objections and the arguments that address each one. The below article addresses the principle of causality and the need for an uncaused first cause:
Unprovable Causality. Since all forms of the cosmological argument depend on the principle of causality (see Causality, Principle of), it would fail without the principle. But can that principle be proved? Normally we think it is obvious, based on experience. But experience may be illusion. Everything not based on experience is simply a tautology, that is, true only by definition and so not proof in itself.
This critique springs from Hume’s epistemological atomism—that all empirical impressions are “entirely loose and separate.” Hume believed necessary causal connection could not be established empirically from sensible experience. But causality is supported by metaphysical necessity. We need not rely solely on empirical observation. Hume himself never denied that things have a cause for their existence. He said, “I never asserted so absurd a proposition as that anything might arise without a cause” (Hume, 1:187).
It would be ontologically ill-advised to suppose that something could arise from nothing. The principle of causality used by Aquinas is that “every limited being has a cause for its existence.” This principle is based in the fundamental reality that nonexistence cannot cause existence; nothing cannot produce something. It takes a producer to produce (see Causality, Principle of).
The need for a cause of existence is rooted in the nature of finite, changing beings as composed of existence (actuality or act) and essence (potentiality or potency). Existence as such is unlimited; all limited existence is being limited by something distinct from existence itself (this limiting factor will be called “essence”); whatever is being limited is being caused, for to be limited in being is to be caused to be in a certain finite way. A limited existence is a caused existence.
Rather, all limited beings are composed beings, composed of existence and essence. Their essence limits the kind of existence they can have. Likewise, an unlimited Being is an uncomposed Being (i.e., a Simple Being). Such a Being has no limiting essence as such. Its essence is identical to its unlimited existence. The need for causality, then, is derived from an analysis of what finite being is. Upon examination, finite being is seen to be caused being, and caused being must have a cause.
Geisler, N. L. (1999). In Baker encyclopedia of Christian apologetics (p. 288). Grand Rapids, MI: Baker Books.