Aquinas's Five Ways: Reason, Faith, and Their Limits
This paper examines Thomas Aquinas's Five Ways — his five classical arguments for the existence of God — and argues that each proof, despite its rational structure, ultimately rests on an assumed foundation of faith. Working through each Way in sequence, the paper explains Aquinas's core logic, identifies the point at which faith substitutes for demonstration, and offers philosophical and scientific objections to each argument. Topics include the arguments from motion, efficient causation, contingency, degrees of perfection, and the governance of natural things. The paper concludes that faith, by its very nature, resists proof, and that Aquinas's reasoning reflects the unquestioned theological assumptions of his era.
- Introduction: Thesis: each Way assumes faith as foundation
- The First Way: Motion and Change: Argument from change ends with assumed God
- The Second Way: Efficient Cause: Causal order attributed to divine first cause
- The Third Way: Contingency and Necessity: Contingent beings require a necessary God
- The Fourth Way: Degrees of Perfection: Supreme goodness assumes God as pure virtue
- The Fifth Way: Governance of Natural Things: Natural patterns attributed to divine guidance
- Conclusion: Faith ultimately underlies all five proofs
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What makes this paper effective
- The paper consistently applies a two-part structure within each section: it first explains Aquinas's argument in accessible terms, then immediately raises a specific objection, keeping the analysis focused and readable.
- The author uses a clear unifying thesis — that faith is the hidden skeleton of each proof — and returns to it throughout, giving the paper coherent argumentative momentum.
- Quotations from primary and secondary sources are deployed precisely to mark the moment each Way concludes with a faith-based assertion, making the textual evidence visible to the reader.
Key academic technique demonstrated
The paper demonstrates close philosophical reading paired with immanent critique — rather than rejecting Aquinas from an external standpoint, it enters each argument on its own terms and identifies the internal moment where logical demonstration gives way to assumption. This technique is especially well suited to analyzing historical theological texts.
Structure breakdown
The paper opens with a framing thesis, then devotes one section to each of the Five Ways in canonical order, maintaining parallel internal structure throughout. A brief conclusion synthesizes the cumulative finding. The Works Cited section follows standard academic citation conventions. Total length is moderate, appropriate for an undergraduate philosophy essay that surveys a multi-part argument without exhaustive depth on any single proof.
Introduction
The Five Ways — Thomas Aquinas's celebrated arguments for the existence of God — are widely regarded as some of the most practical and substantive philosophical proofs ever composed on the subject. Though they possess considerable merit, the reality of each argument both begins and ends with simple faith. The reader or philosopher is ultimately left to interpret Aquinas's logic through statements that all conclude with an assumption of faith, making faith the very structure and skeleton of his proofs.
Though his works are well thought out, they were created in an era when questioning ultimate truths was virtually unheard of. The faith of Aquinas, and of the whole period in which he wrote, is assumed throughout the dialogue of his proofs, in many ways reducing each individual proof to yet another representation of faith. This paper will briefly explain and define each proof and then attempt to demonstrate the point at which faith enters each of the Five Ways and the arguments associated with it.
In the entire set of proofs, Aquinas demonstrates the use of reason and scientific thought. He spends considerable effort formulating, both for himself and for the reader, explanations of each preceding assertion. With or without these explanations, it is clear that he is speaking to an audience that both assumes and believes that God exists. Even today, "many human beings have reasons for such a belief that are informal versions of one of the five ways; they suppose, for example, that because there is order in the universe there must be a principle of order" (Hibbs 573).
The First Way: Motion and Change
In the First Way, Aquinas relates the existence of God to the process of change. He states that within this world all people admit that things exist which are in the process of change, and that this change is initiated by a force other than the thing itself. Aquinas then argues that if this is the case — and he asserts that it obviously is — there must have been an initial force that changed something into something else, because a thing cannot simultaneously be what it is and what it has the potential to be.
Closing the argument, Aquinas attributes the property of this initial force of change to God, since the process cannot be infinite in either direction and must therefore have a finite first cause. "So we have to come to some first initiator of change which is not in a process of change initiated by something else, and everyone understands that this is God" (Martin 134).
Clearly, Aquinas frames his argument within a particular historical context, charging "everyone" with a belief in God and thus invoking a blindly assumed tenet of reality — an unchangeable fact of life. Refutation of this argument is fairly straightforward and accepted by millions: the very nature of faith is that it is blind. Faith cannot be affirmed by proof, because once it is proven it is no longer faith.
The Second Way: Efficient Cause
In the Second Way, Aquinas comes closest to outlining what many would consider the law of nature. Within nature there is a pattern or order of things and events; these patterns are observable and tend to exemplify the best possible outcomes repeatedly. The principle at work here is that if this kind of optimal order or pattern exists, there must be a source of that plan — and that source would be the divine.
The Second Way attempts to demonstrate a clear link between the notion of efficient cause and an ultimate source for such a cause. Excluding itself as the source of the efficient cause, Aquinas once again assumes the existence of a divine power called God who defines and embodies the initial and continuing most-efficient cause:
"We find, in things around us that we sense, an order of efficient causes. But we do not find — nor could there be — anything that is the efficient cause of itself. For if anything were, it would have to be prior to itself, and this is impossible." (Martin 150)
Once again Aquinas dismisses the infinite by asserting simply that people must exclude it as a possibility. The simplest argument against this is that human beings, as finite minds, are simply unable to conceive of the infinite — a testament to the limitations of the human mind rather than to the finite nature of the universe. Finitude must assume a series of causes — first, last, and intermediary — and according to Aquinas the only possible solution is that God is the initial efficient cause. "Hence we must suppose some first efficient cause, and this is what all call 'God'" (Martin 151).
A further objection is that all things have a beginning and an end as what they are. Before they exist, they are simply potential. Their matter may exist, but the essential "what" of the thing is not present until it is actualized.
Conclusion
Challenging faith is nearly always a very serious endeavor. The ideals associated with Thomas Aquinas's Five Ways are clearly shaped by his era's scientific assumptions and the representative faith of his time. With or without the expression of his logical thought, the remaining formation of each Way is eventually reduced to an expression of faith.
"There can be no science where there is no quiddity or essence, as for example a science of the unicorns sung about by Irishmen. Logic doesn't study natures absolutely considered. It studies the formal relations or intentions that accrue to natures as known, that is, that accrue to natures in the mode of existence that they have in anima." (O'Callaghan 69)
Faith, by its own virtue — absent of being and matter — is an expression of the assumed and the unknowable. Each Way, one by one, can be explained and objected to on grounds of assumed faith; yet within each is also a means of demonstrating that faith can reduce the validity of any objection. The ongoing philosophical debate over Aquinas's proofs reflects precisely this enduring tension between reason and belief.
Hibbs, Thomas S. "Aquinas, Virtue and Recent Epistemology." The Review of Metaphysics 52.3 (1999): 573. Questia. 30 Nov. 2003.
Martin, C.F.J. Thomas Aquinas: God and Explanations. Edinburgh: Edinburgh University Press, 1997.
O'Callaghan, John. "Concepts, Beings and Things in Contemporary Philosophy and Thomas Aquinas." The Review of Metaphysics 53.1 (1999): 69. Questia. 30 Nov. 2003.
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