St. Thomas Aquinas’s Quarta Via (Fourth Way) forms part of his famous Quinque Viae (Five Ways) found in his Summa Theologiæ, which collectively provide arguments for the existence of God. The Fourth Way, often summarised as, “If things are more and less good, there must be a best, and this something is God,” offers an insightful exploration of being and perfection. However, such simplifications risk diluting Aquinas’s rigorous metaphysical reasoning, which is deeply embedded in Aristotelian thought. This article unpacks the Fourth Way in detail, showing how Aquinas constructs an argument from observable phenomena, specifically gradations of goodness, truth, and nobility, to the existence of a being that is the cause of all perfections—God.
Understanding the Context of the Fourth Way
Aquinas’s arguments for the existence of God rely on what he calls “God’s effects”—observable features of the world that necessitate a cause. For Aquinas, reasoning about God cannot proceed directly from abstract definitions, as humans cannot comprehend God’s essence fully. Instead, he builds his proofs from empirical realities, from what we observe in the world around us. The Fourth Way begins with a focus on gradations, observable differences in qualities such as goodness, truth, and nobility.
Aquinas notes that we find some things to be “more” or “less” good, true, noble, and so on, and that these gradations imply a hierarchy. From this, he argues that there must be something that is the maximum of all these qualities and that this maximum must exist in a supreme way. This “maximum” is what he identifies as God.
The Argument from Gradation: A Closer Look
Step 1: Observing Gradations
Aquinas begins by acknowledging a self-evident truth: within our experience, we observe varying degrees of qualities such as goodness, truth, and nobility. For instance, we can say that one person is more virtuous than another, or that one artwork is more beautiful than another. These comparative assessments presuppose a scale, or gradation, by which things are evaluated.
Step 2: The Need for a Standard
The existence of gradations implies a standard or reference point. When we say one thing is “better” or “more noble” than another, we implicitly refer to a concept of what is “best” or “most noble.” Without this maximum, our evaluations would lack coherence, as there would be no objective measure to ground such comparisons.
Step 3: The Principle of Participation
Aquinas draws upon Aristotelian metaphysics to argue that things possessing qualities in degrees must “participate” in the quality itself. For example, a warm object participates in the quality of warmth but does not possess it to the maximum degree. Similarly, all good things participate in goodness but are not the fullness of goodness itself.
Step 4: The Existence of a Maximum
Aquinas concludes that for these gradations to exist, there must be something that embodies the quality to its fullest extent—its “maximum.” This maximum is not simply the greatest instance of the quality but is the very essence of the quality itself. For example, the maximum of goodness is not merely the “best thing” but the source and standard of all goodness.
Step 5: Identifying the Cause
Finally, Aquinas asserts that this maximum must be the cause of all instances of the quality. Drawing again from Aristotelian thought, he argues that the bestowing of a quality presupposes a source. Therefore, the maximum of goodness, truth, or nobility must be the cause of all that is good, true, or noble. This ultimate cause is what Aquinas identifies as God.
Goodness, Truth, and Being: An Interwoven Reality
A crucial aspect of Aquinas’s metaphysical vision, as emphasised by Brian Davies and others, is the intrinsic connection between goodness, truth, and being. These are not separate or unrelated qualities but are deeply intertwined. Aquinas draws upon the philosophical tradition that understands these attributes as transcendentals—features of all that exists, reflecting the very nature of reality.
Being as the Foundation
For Aquinas, all things that exist share in being to varying degrees. To exist is to be, and to be more fully is to reflect greater goodness and truth. For example, consider a skilled carpenter creating a beautifully crafted table. The table, as an object, “participates” in being more fully than a poorly constructed one. Its structure, durability, and utility embody a greater perfection, reflecting the carpenter’s skill and intent. Similarly, a wise person, in their pursuit of truth and moral excellence, “participates” more fully in being than someone who acts dishonestly or destructively.
Goodness and Truth as Dimensions of Being
Goodness and truth are dimensions of being itself. When something is good, it fulfils its purpose and realises its potential—it is, in a fuller sense. A musician excelling in her craft not only demonstrates technical skill but embodies a deeper truth about what it means to be human: the pursuit of excellence, harmony, and expression. In such moments, she “shares” in the divine, aligning her being with the ultimate source of goodness and truth, which is God.
Similarly, truth is not just factual accuracy but alignment with reality as it is. A scientist who uncovers the laws of nature participates in truth by uncovering the order woven into the fabric of existence. This alignment with reality is simultaneously an alignment with being itself, as all truth ultimately originates from the divine intellect.
Excelling in Goodness and Truth: Sharing in Divine Being
When we excel in goodness or truth, we participate more fully in being itself. For Aquinas, this means sharing in the very essence of God, who is the fullness of being (ipsum esse subsistens). The closer something aligns with its purpose or realises its potential, the more it reflects God’s perfection. Consider a parent nurturing a child with love and wisdom. In fulfilling this role, the parent mirrors divine goodness, bringing more “being” into the world by fostering life, love, and growth.
This perspective illuminates why Aquinas’s Fourth Way ties the existence of God to observable gradations of goodness and truth. These gradations are not arbitrary but reflect the extent to which things participate in being itself. The highest expression of being—pure actuality, without limitation or defect—is what Aquinas identifies as God.
Objections and Clarifications
The Fourth Way, while compelling, has faced criticism over the centuries. Here, we address some of the most common objections and provide clarifications.
- The Leap from the Maximum to God
Critics often argue that Aquinas makes an unjustified leap from the existence of a maximum to the assertion that this maximum is God. However, Aquinas’s reasoning is grounded in his understanding of causality. For Aquinas, God is not merely the greatest being among others but the very essence of being itself. Thus, the maximum of any quality must necessarily coincide with God, who is the source of all being and perfection.
- The Relativity of Qualities
Some question whether qualities like “goodness” and “truth” are truly objective or merely subjective human constructs. Aquinas would counter that the very ability to perceive gradations presupposes an objective standard. Without a real grounding in a maximum, comparative statements about goodness or nobility would be meaningless.
- The Problem of Evil
Aquinas’s argument seems to imply a perfect source of goodness, yet the world contains evil and imperfection. Aquinas addresses this elsewhere in his works, asserting that evil is not a substance or a quality in itself but a privation or lack of good. The existence of a perfect maximum does not negate the presence of lesser goods or privations but rather explains why we recognise them as imperfect in the first place.
The Broader Implications of the Fourth Way
The Fourth Way has significant implications for understanding Aquinas’s overall vision of reality. It reinforces the idea that God is not a being among beings but the very foundation of all existence and perfection. By situating God as the maximum of all qualities, Aquinas integrates metaphysical principles with theological claims, providing a unified vision of reality where God is both transcendent and immanent.
Moreover, the argument highlights the interconnection between goodness, truth, and being. For Aquinas, these transcendentals are not merely abstract ideas but attributes of God himself, who is their ultimate source and exemplar.
Conclusion: The Enduring Relevance of the Fourth Way
The Fourth Way of St. Thomas Aquinas is a testament to the enduring power of metaphysical reasoning. While modern readers may find it challenging to engage with its Aristotelian framework, the argument continues to provoke deep philosophical reflection on the nature of goodness, truth, and being. By linking observable phenomena to a divine cause, Aquinas provides a pathway to understanding God not as a distant entity but as the very ground of all that is.
Whether one accepts or critiques the Fourth Way, it remains a vital contribution to the history of philosophy and theology. It invites us to see the world not as a collection of disconnected phenomena but as a cosmos infused with meaning, order, and purpose—a cosmos that ultimately points beyond itself to its divine source.
Meta Description: Explore St. Thomas Aquinas’s Fourth Way, linking goodness, truth, and being to the divine source of all existence in a cosmos of order and purpose.
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