Kant’s Influence on Neo-Thomistic Views of Human Person

When philosophers ask “what does it mean to be human?”, they are not simply asking a biological question. They are reaching for something deeper – the nature of selfhood, freedom, moral responsibility, and our relationship to what lies beyond us. Two major intellectual traditions have taken up this question with remarkable depth: the critical philosophy of Immanuel Kant and the Neo-Thomistic movement that followed in his wake. Understanding how Kant’s ideas seeded a rich tradition of thought about the human person – particularly through thinkers like Joseph Maréchal and Karl Rahner – opens a fascinating window into Western philosophy’s most ambitious attempt to account for what we are.

Kant’s transcendental self: the human person as rational agent 🔗

At the heart of Kant’s philosophy is a radical shift in how we think about the self. Rather than treating the human person as just another object in the world, Kant placed the active, rational human subject at the very center of both the cognitive and moral worlds. This is what he meant by the transcendental self – not the empirical “me” of everyday experience, but the deeper, underlying structure of consciousness that makes experience possible in the first place.

According to Kant, the human self – what he called the transcendental ego – constructs knowledge out of sense impressions using universal concepts called categories that it imposes upon them. In other words, we do not simply receive the world passively. The mind actively organizes raw sensory data into coherent experience. Space, time, and causality are not features we discover “out there” – they are structures the mind brings to experience. This doctrine, known as transcendental idealism, drew a sharp distinction between the world as it appears to us (phenomena) and things as they are in themselves (noumena), which remain permanently beyond our knowledge.

This has a profound implication for how we understand the human person. Kant argued that the mind necessarily makes a constitutive contribution to knowledge, and that to act autonomously is to act according to rational moral principles. We are not merely passive observers of reality – we are its active co-constituters. And that same rational capacity that structures our knowledge is also the ground of our moral life.

The categorical imperative and the dignity of persons 🔗

Kant’s view of the human person is perhaps most powerfully expressed in his moral philosophy. Kant argued that the supreme principle of morality is a principle of rationality he called the Categorical Imperative – an objective, rationally necessary, and unconditional principle that all rational agents must follow regardless of their desires. Unlike hypothetical imperatives (which bind us only if we have certain goals), the categorical imperative binds us simply because we are rational beings.

Its most famous formulation – act only according to that maxim by which you can at the same time will that it should become a universal law – is grounded in a vision of the human person as inherently dignified. This moral law obliges us to treat humanity – understood as rational agency – as an end in itself rather than merely as a means to other ends. Every person, by virtue of their rational nature, commands respect. This is not sentiment or convention – it is, for Kant, a demand of reason itself.

Equally important is Kant’s insistence on moral autonomy. He argued for the idea of transcendental freedom – freedom as a presupposition of the moral question “what ought I to do?” – as the basis for ascribing moral responsibility, calling it the rational and self-actualizing power of a person. We are not simply determined by nature or inclination. We are capable of giving ourselves the moral law through reason alone. This makes the human person something genuinely unique in the natural world.

The limits Kant left open – and why they mattered 🔗

Despite its power, Kant’s framework imposed strict limits on what reason can know. God, the soul, and ultimate reality belong to the noumenal realm – they cannot be objects of theoretical knowledge. Kant famously said he had to deny knowledge to make room for faith. By relegating God and the soul to an unknowable realm of things in themselves, Kant guaranteed that it is impossible to disprove claims about God and human freedom – and that moral arguments could justify belief in them. But he did not integrate them into a positive account of the human person’s orientation toward the divine.

This is precisely where Neo-Thomism stepped in. Catholic philosophers and theologians – inheritors of the rich intellectual tradition of Thomas Aquinas – saw in Kant both a profound contribution and an unfinished project. His dynamic account of the knowing subject was deeply suggestive. But his refusal to let reason reach beyond phenomena seemed, to them, to cut the human person off from the very transcendence that defines us most deeply.

Joseph Maréchal: bridging Kant and Aquinas 🔗

Joseph Maréchal (1878-1944) was a Belgian Jesuit philosopher and the founder of the school of thought known as Transcendental Thomism, which attempted to merge the theological and philosophical thought of Thomas Aquinas with that of Immanuel Kant. His landmark work, the five-volume Le Point de Départ de la Métaphysique, engaged Kantian philosophy not to refute it but to push it further.

Maréchal’s key insight was that Kant had discovered something real about the mind’s dynamic activity – its active role in structuring experience – but had not fully appreciated what that dynamism implies. Maréchal appreciated Kant’s notion that the mind is active and dynamic in its structuring of what it knows, but argued that Kant failed to honor the full character of this dynamism – which is not merely open-ended but oriented toward a specific end, namely Absolute Being. The mind does not just organize experience; in every act of knowing, it implicitly reaches toward the infinite. This is not a leap of faith – it is, for Maréchal, a philosophical necessity built into the very structure of human cognition.

Maréchal argued that the most important a priori condition of consciousness – which Kant failed to recognize – is the intellectual dynamism of the subject, its activity in constructing the immanent object, whose formal object is Absolute Being. In this way, Maréchal transformed Kantian epistemology from within, using its own tools to arrive at a metaphysics Kant had deliberately foreclosed. Through his pioneering intellectual efforts, Maréchal showed Catholic thinkers that they could be faithful to the spirit of Thomas Aquinas while engaging in critical conversation with other philosophical traditions.

Karl Rahner: the human person as spirit in the world 🔗

No thinker did more to develop Maréchal’s synthesis into a comprehensive philosophy of the human person than Karl Rahner (1904-1984). Rahner’s philosophy forwards a unique transcendentalism from Thomism, featuring the Heideggerian rootedness of human being in its world, the Rousselotian identity of knowing and being as spirit, and the Maréchalian themes of the endless dynamism of mind and the intrinsic co-affirmation of absolute being in that dynamism.

Rahner’s philosophical masterwork, Geist in Welt (Spirit in the World), reinterpreted Aquinas’s epistemology through a Kantian-Maréchalian lens. Rahner views humanity as embodied spirits, historically situated in a concrete existence of freedom and temporality, where every mundane experience is in some sense ordered toward and grounded in the Infinite. This is not a dualism of soul trapped in body – it is a vision of the human person as a dynamic unity of spirit and matter, always already engaged with the world but always also reaching beyond it.

For Rahner, transcendence is not an optional add-on to human life – it is constitutive of what we are. Rahner borrows Kantian language to describe this orientation as “transcendental,” arguing that explicit proofs for God’s existence ultimately refer back to the inescapable orientation toward mystery that constitutes, by transcendental necessity, the very nature of the human being. We do not choose to be oriented toward the infinite any more than we choose to be rational. It is part of the structure of human consciousness itself.

The dynamic interplay of spirit and matter 🔗

One of Rahner’s most significant contributions is his treatment of the relationship between spirit and matter in the human person. Where Descartes had driven a sharp wedge between mind and body, and where Kant’s transcendental self could seem detached from its material conditions, Rahner insists on their deep integration. The human person is a form of the unity of spirit and matter – it is only in a human person that spirit and matter can be experienced in their relationship.

This means that the human person is not a spirit that happens to have a body, but a being whose spirituality is always mediated through materiality and history. We know the infinite only through engagement with the finite. We encounter the divine only through the concrete, the particular, the embodied. This is why Rahner develops his theology as an analysis of human experience and its transcendental and historical conditions, arguing that human knowledge and freedom transcend themselves in an unbounded way, only possible against an infinite horizon grasped in a dim but ever-present pre-apprehension.

Transcendental experience and the horizon of the absolute 🔗

Rahner uses the concept of Vorgriff – a pre-apprehension or anticipatory reach – to describe the way every human act of knowing and choosing implicitly orients us toward the totality of being. Rahner calls this “transcendental experience” because it creates the condition of possibility for all categorical experience, and because it transcends any particular human experience or historical moment. In this, the debt to Kant is clear: just as Kant showed that the mind brings a priori structures to experience, Rahner argues that the human person brings a prior orientation to the Absolute to every encounter with the world.

But where Kant stopped at the limits of theoretical reason, Rahner pushes further. The infinite horizon that makes finite knowledge possible is not a blank wall but what Rahner calls Holy Mystery – the inexhaustible transcendence that grounds all human experience and invites the human person into an ever-deeper relationship.

What Kant’s influence on Neo-Thomism means for understanding the human person 🔗

The dialogue between Kant and Neo-Thomism is not merely a historical curiosity. It reflects a deep conviction shared by both traditions: that the human person cannot be reduced to biology, sociology, or psychology alone. Kant brought to crescendo the “philosophy of the subject” that had been steadily on the rise, and this Kantian impetus became the foundation for a Neo-Thomistic account of the dynamic, searching character of the human mind as ultimately rooted in its trajectory toward the Absolute.

Kant’s legacy – the transcendental self, the moral dignity of persons, the centrality of practical reason – gave Neo-Thomism the conceptual tools to articulate what Aquinas had intuited: that the human person is not merely a rational animal, but a being constitutively open to transcendence. Rahner’s program reformulated Thomism’s epistemology, philosophical anthropology, and metaphysics as transcendental philosophy, producing one of the most ambitious accounts of the human person in modern thought.

Together, Kant, Maréchal, and Rahner offer a vision of the human person as a being who is always in the world, always embodied and historical, but also always reaching beyond – toward truth, toward freedom, toward an infinite horizon that cannot be contained within any finite category. The human person, on this view, is defined not by limits but by an irreducible capacity for transcendence.

What do you think? Does Kant’s insistence that the moral worth of an action lies entirely in its rational motive – rather than its outcomes – capture what you believe makes human beings truly dignified? And if the human person is, as Rahner argues, constitutively oriented toward an infinite horizon, does that change how we should understand freedom, responsibility, and the meaning of a human life?

References

1. https://plato.stanford.edu/entries/kant/
2. https://www.britannica.com/topic/transcendental-idealism
3. https://plato.stanford.edu/entries/kant-moral/
4. https://en.wikipedia.org/wiki/Immanuel_Kant
5. https://en.wikipedia.org/wiki/Categorical_imperative
6. https://en.wikipedia.org/wiki/Joseph_Mar%C3%A9chal
7. https://iep.utm.edu/rahner/
8. https://www.encyclopedia.com/humanities/encyclopedias-almanacs-transcripts-and-maps/marechal-joseph-1878-1944
9. https://utppublishing.com/doi/pdf/10.3138/uram.22.4.264
10. https://catholicstarherald.org/rahners-influential-transcendental-thomism/
11. https://en.wikipedia.org/wiki/Karl_Rahner
12. https://scriptoriumdaily.com/how-to-read-karl-rahner/
13. https://people.bu.edu/wwildman/bce/rahner.htm
14. https://www.cambridge.org/core/books/abs/cambridge-companion-to-karl-rahner/rahners-transcendental-project/F3EF723A3E54EDB4D61BBEC7534D7528