Aquinas and Proof of the Existence of God

What, one may ask, is the meaning of life?

An ultimate question. The most common approach in the rhetoric of the post-enlightenment, secularist consensus is effectively not to answer it; instead, to accept the apparent and ultimate meaningless of human existence, focusing on forging one’s own meaning. This liberal methodology is a rejection of a form of ‘Higher Authority’, and choses to ignore a series of existential problems that arise from such rejection. For that, after all, could be interpreted as the humane ‘purpose’ of God: to provide rationality in the face of ‘absurdity’, as much as piety would dictate that God cannot, or should not, be rationalised.

To ignore the problems arising from the rejection of God, however, could be conceived as fooling oneself of the reality of a world without a Supreme Being, in which man is meaningless beyond his material existence. It is curious to consider, though, that the acceptance of God as a philosophical node, without adherence to what might be termed social or organised religion, can provide answers to a series of ontological and existential paradoxes. That is not to imagine God as one might in Christian theology, or any other theology for that matter, but to accept a ‘Supreme Being’ as rationality. Thomas Aquinas, the Catholic philosopher and theologian, wrote, in the 13th Century, the Quinque Viae, or ‘Five Proofs’ to justify the existence of God, which remain conceptually viable and of somewhat distinct value. The proofs tackle two fundamental problems of existence: ‘infinity’ and the ‘ultimate’.

Defeating Infinity

The ‘Five Proofs’ begin with three cosmological arguments that serve as philosophical answers to what are effectively physical-scientific paradoxes. The first, that of the ‘unmoved mover’, argues that a Supreme Being is the initial catalyst for movements, more generally defined as ‘existence’, in the universe. It runs that some entities move, but that nothing can ultimately move itself; everything must instead be moved. If, therefore, one entity is moved by another, then it stands to reason that there must be infinite movers, which, given that the material world is fundamentally finite, is impossible. Hence, it can be argued that there must be an immaterial ‘unmoved mover’, substituting for the idea of an infinite regression of movers; Aquinas argued that such a figure was what we on Earth refer to as God.

The second ‘proof’ runs along similar logic to the first, arguing that God must too have been the creator of the universe by analysing causation. It runs that some things are caused by other things, which in turn are caused, but again, there cannot be an infinite number of worldly causes. There must, therefore, be an immaterial ‘uncaused cause’, in a similar vane to the ‘unmoved mover’, which can be interpreted as God. These two arguments effectively play on the inability of humanity to conceptualise infinity in a finite material world, providing the rationality of infinity through the projection of God.

The third ‘proof’ follows the two initial cosmological arguments, focusing on the contingency of material things. It runs that all entities in the universe are contingent, i.e. they exist or do not, and that they are finite, but that it is impossible for all entities in the universe to be contingent, as it would follow that there must have been a time when all entities did not exist. An entity-less universe is incomprehensible for the reasons discussed in the initial two proofs: that there must be an ‘unmoved mover’ and an ‘uncaused cause’. There must, therefore, exist a being whose existence is not contingent on that of any other entity, in order to counteract the paradox of complete anti-existence. The rationale for this, according to Aquinas, is God.

Defeating the Ultimatum

The fourth and fifth ‘proofs’ are slightly in variance of the initial three, and deal with crises of the unknown ultimate in a material world. The argument from degree, the fourth, posits on the concept of perfection, and is based heavily upon Aristotelian ideas. It runs that every entity in the universe sits upon a degree of perfection, and that therefore, it is assumed that there is an ultimate perfection beyond the greatest degree of perfection known to the material universe. It is logical to assume that, as we can never know if we have reached ultimate perfection, that perfection must have a pinnacle beyond this finite world. Aquinas argues that this pinnacle of perfection is in fact God, accounting again for the lack of humane ability to comprehend ideas beyond this finite world.

Aquinas’ final ‘proof’ is one of teleology, based on the assumption that worldly beings, by nature of being worldly, are unintelligent and are moving through a teleological space under the guise of another being. If all entities move towards ends, and follow rules be they physical or metaphysical, then they must be intelligent in order to do so; but, given the first four arguments for the existence of God, all entities, in a vacuum, are unintelligent. Moving towards an end, though, is a fundamental characteristic of consciousness and intelligence, and it hence follows that there must exist an intelligent entity to guide the amalgamated unintelligent beings toward ends. This intelligence, Aquinas called God. Perhaps the final proof is the easiest to pull apart, given the liberal focus on human intelligence and self-determination. But, just like Aquinas’ doctrine, liberalism assumes too much to arrive at such conclusions without reasoned argument.


Interestingly, contrary to criticism from scientific atheists such as Richard Dawkins, Aquinas, in his ‘Five Proofs’ at least, does not arrive at God arbitrarily, nor through determination. Instead, Aquinas finds five rational answers to existential paradoxes, which he suggests are the work of a ‘Supreme Being’. Whether or not atheism can ever appreciate Thomist logic is a different matter; but it is interesting, from an academic standpoint to consider the use of God as a rational resolution of paradox, rather than initial, and/or perhaps unfounded, faith.


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