God, Being and Existence: Proofs, Critiques and the Fundamental Question

“Does God exist?” is perhaps the oldest and most persistent question in philosophy. It has accompanied Western thought from the earliest Presocratics — when Xenophanes of Colophon (c. 570–c. 475 BC) criticized the anthropomorphism of Homer’s gods — to contemporary analytic debates on modal logic and Bayesian probability. And yet, posed in these terms, the question conceals a trap. For before asking whether God exists, one must ask what it means, for God, to exist. Here a decisive distinction opens up — one that separates philosophically rigorous theism from conceptual idolatry: the distinction between existing (existere) and being (esse).

This article traces, with historical and doctrinal rigor, the classical arguments for God’s existence, the decisive objections they have received, and the metaphysical reformulation that culminates in a paradoxical realization: strictly speaking, God does not exist — God is.

1. The fundamental distinction: existere and esse

1.1 The etymology and the problem

The Latin verb existere derives from ex-sistere: “to step out of”, “to emerge from”, “to stand forth from” a background. To exist, in the strict sense, is the mode of being proper to that which might not be — which has received being, which “stands forth from” an origin that is not itself. Every creature, in this strict sense, exists: for its being does not belong to it by essence but is given to it.

The verb esse, by contrast, designates the pure act of being, without dependence, without participation, without reception. For the tradition that culminates in Thomas Aquinas, to say that God “exists” in the same sense in which a stone or a human being exists is to commit a categorial error: it places God on the line of beings, as if He were the greatest of them, instead of recognizing Him as the ground of every being.

1.2 Exodus 3:14 and the metaphysics of Exodus

The biblical passage Exodus 3:14 — in which God, asked by Moses for His name, answers Ehyeh asher ehyeh (Hebrew: “I am who I am”; Vulgate: Ego sum qui sum) — became, in the history of thought, the point of articulation between revelation and metaphysics. Étienne Gilson (1884–1978) coined the expression “metaphysics of Exodus” to designate the convergence between the self-identification of the biblical God as Being and Aristotelian first philosophy as refounded by Aquinas. God’s name is no ordinary name: it is the very act of being.

1.3 Ipsum esse subsistens: the Thomistic thesis

In Thomas Aquinas (1225–1274), the central metaphysical thesis of the doctrine of God is condensed in a formula: God is ipsum esse subsistens — “the subsistent act of being itself” (Summa Theologiae I, q.4, a.2; q.13, a.11). In all created beings there is real composition between essence (essentia: what something is) and act of being (esse: that something is). In God, and in God alone, essence and act of being coincide: His essence is to exist. This thesis, already developed in De ente et essentia (c. 1252–1253, ch. 4), is the key that supports Thomas’s entire natural theology.

The consequence is radical: God is not a being — even the greatest; God is the act by which every being is. To deny this distinction is, according to Aquinas, to make God a creature — perhaps infinite, perhaps perfect, but still limited to the category of being.

2. The classical proofs of God’s existence

Over two millennia, philosophy has produced a fairly stable set of arguments for God’s existence. Three great families are traditionally distinguished: the ontological (from the concept of God), the cosmological (from the world and its general features — motion, causality, contingency), and the teleological (from the order and finality of the world). To these is added, in modernity, the moral proof (Kant).

2.1 The ontological argument: Anselm of Canterbury

Anselm (c. 1033–21 April 1109), Archbishop of Canterbury, formulated in the Proslogion (1077–1078) what would become known — through Kant’s nomenclature — as the ontological argument. Anselm conceived it as a single proof capable, by itself, of grounding all natural theology.

The opening definition is the key: God is “that than which nothing greater can be thought” (id quo nihil maius cogitari possit, Proslogion II). Even the fool (insipiens) of Psalm 14 — who says in his heart “there is no God” — understands the expression. Therefore that than which nothing greater can be thought exists at least in the intellect. But if it existed only in the intellect, one could think of something greater — namely, this same that existing also in reality. Therefore that than which nothing greater can be thought must exist both in the intellect and in reality.

Chapter III of the Proslogion pushes the argument further: God cannot even be thought as not existing. For what can be thought as not existing is lesser than what cannot. Therefore God necessarily exists — and the fool, in saying that God does not exist, either does not understand the words he utters, or understands them and contradicts himself.

Gaunilo’s objection

The monk Gaunilo of Marmoutier (11th century) responded in the Liber pro insipiente (“Book in Favor of the Fool”): by the same method one could prove the existence of a perfect island — that island than which no greater can be thought. Since an island that exists is greater than one merely thought, the perfect island would necessarily exist. Reductio ad absurdum.

Anselm replied in the Responsio: the objection fails because the concept of a “perfect island” is contradictory — an island, by definition, is a finite and contingent being. Only in God is the concept of “that than which nothing greater can be thought” non-contradictory, because only God possesses necessary being. The argument, therefore, works for God alone.

2.2 The Five Ways: Thomas Aquinas

Thomas, at the beginning of the Summa Theologiae (I, q.2, a.3, written between 1265 and 1268), rejects the Anselmian argument on methodological grounds: for us, in the human condition, God’s existence is not self-evident, although it is so in itself; we must therefore prove it from effects. Hence the Five Ways, all of them a posteriori and cosmological:

1. Way of motion (ex motu): everything that moves is moved by another. Since the chain of moved movers cannot regress to infinity without suppressing actual motion, there must be a First Unmoved Mover — quod omnes intelligunt Deum, “what all men understand to be God”.

2. Way of efficient causality (ex ratione causae efficientis): nothing is the efficient cause of itself; the chain of subordinated efficient causes requires a First Uncaused Cause.

3. Way of the possible and the necessary (ex contingentia): there are beings that can be and not-be. If everything were contingent, at some point nothing would have existed — and nothing could have begun to exist. Therefore there must be a Necessary Being, whose necessity derives not from another but from itself.

4. Way of the degrees of perfection (ex gradibus): there are degrees of goodness, truth, nobility in things. The comparative presupposes a superlative: there must exist that which is maximal in being and perfection, cause of every perfection in others.

5. Way of the governance of things (ex gubernatione rerum): natural beings lacking intelligence act for an end. What acts for an end without knowing it must be directed by an ordering intelligence — as the arrow is directed by the archer.

The Five Ways are not five isolated proofs: they are five approaches starting from different aspects of experience (motion, causality, contingency, perfection, finality) and converging on a reality that deserves the name “God.” Each Way ends with the formula et hoc dicimus Deum or its equivalent — “and this we call God” — making explicit that the argument establishes an ultimate reality whose identification with the God of faith demands further demonstrations (which occupy questions 3 to 26 of the Prima Pars).

2.3 The Cartesian ontological argument

René Descartes (1596–1650), in the Fifth Meditation (1641), reformulates Anselm’s argument in modern terms: the idea of God contains the notion of a supremely perfect being; existence is a perfection; therefore existence belongs to God’s essence just as having three angles equal to two right angles belongs to the essence of a triangle. I cannot think God without existence, just as I cannot think a mountain without a valley. The difference is that, in the case of a mountain, the impossibility of thinking it without a valley does not imply that mountains exist; but in the case of God, the impossibility of thinking Him without existence implies that He exists — for existence is one of His perfections.

2.4 Leibniz’s cosmological argument: the principle of sufficient reason

Gottfried Wilhelm Leibniz (1646–1716) gave the cosmological argument its most elegant form in the Monadology (1714, §§32–39) and the Theodicy (1710). The starting point is the principle of sufficient reason: “nothing happens without a sufficient reason why it is so and not otherwise” (Monadology §32).

Applied to the world as a whole: why is there something rather than nothing? The sufficient reason of the world cannot lie in any of the contingent elements that compose it, nor in their sum, for the sum of contingents is itself contingent. The sufficient reason of the world must lie outside the world, in a Being whose reason for being is in itself — a necessary Being existing a se (from itself). And “this final reason of things is called God” (Monadology §38).

Leibniz’s question — “pourquoi il y a plutôt quelque chose que rien?”, “why is there something rather than nothing?” (Principles of Nature and Grace, 1714, §7) — became, in the history of philosophy, the canonical formulation of the fundamental metaphysical question. Heidegger would take it up as the inaugural question of What Is Metaphysics? (1929) and Introduction to Metaphysics (1953).

2.5 The moral argument: Kant

Immanuel Kant (1724–1804) destroyed, in the Critique of Pure Reason (1st ed. 1781), the theoretical proofs of God’s existence — ontological, cosmological, and physico-teleological (the last being the design argument). But in the Critique of Practical Reason (1788), he rehabilitates God as a postulate of practical reason.

The argument in brief: morality requires that virtue be rewarded with happiness — not as the motive for moral action (which would corrupt it into heteronomy), but as an objective requirement of the summum bonum, the “highest good.” In the sensible world, virtue and happiness do not necessarily coincide. For the moral demand not to be absurd, one must postulate: (a) the immortality of the soul, so that indefinite progress in holiness is possible; (b) God, as the being who harmonizes virtue and happiness. God is not theoretically proved — He is practically required as the condition of intelligibility of moral life.

3. The decisive critiques

3.1 Hume and the design argument

David Hume (1711–1776), in the Dialogues Concerning Natural Religion (composed in the 1750s and published posthumously in 1779), submitted the teleological argument — the “divine watchmaker” argument — to one of the most devastating critiques in the history of philosophy. Through the voice of Philo, Hume argues:

• The analogy between the world and a machine (a human artifact) is weak: we know machines because we see craftsmen producing them; we do not know universes being produced.
• The order we observe in the universe could result from other principles: generation, vegetation, instinct, or simply chance operating over sufficient time (a remarkable anticipation of natural selection).
• Even granting a designer, nothing guarantees that it is unique, infinite, perfect or moral. The world might be the work of an apprentice god, or of many gods cooperating imperfectly.

Hume does not aim to demonstrate atheism: he aims to show that natural theology cannot, by its own methods, establish more than a vague analogy between the cause of the universe and human intelligence.

3.2 Kant: “being is not a real predicate”

Kant’s critique of the ontological argument, in the Critique of Pure Reason (B620–B630), formulated one of the most influential objections in modern philosophy. The central thesis is famous: Sein ist offenbar kein reales Prädikat — “Being is manifestly not a real predicate” (B626).

What this means: when I say “God is omnipotent,” “omnipotent” adds a determination to the concept of God. But when I say “God exists,” I add no determination to the concept of God — I assert only that an object corresponds to the concept. A hundred real thalers contain not a cent more, in conceptual terms, than a hundred possible thalers; the difference lies only in whether the real ones obtain, which is not an internal property of the concept.

Kantian conclusion: from the concept of a most perfect being, however much one analyzes it, one will never extract effective existence — because existence is not a conceptual mark. The ontological argument is therefore fallacious.

Kant’s critique equally affects the cosmological argument, which, by appealing to the idea of a necessary being, would in its ultimate affirmation reduce to the ontological. The three traditional proofs — ontological, cosmological, and physico-teleological — fail, according to Kant, as theoretical knowledge.

3.3 Nietzsche: “God is dead”

Friedrich Nietzsche (1844–1900) shifted the problem to a different plane. It is not a matter, in The Gay Science (Die fröhliche Wissenschaft, 1882, §125, “The Madman”), of proving or refuting God’s existence, but of diagnosing a historical and cultural event: the death of God in Western consciousness.

The madman announces, in the middle of the market, that God is dead, and that we have killed him. The phrase does not mean that God ever “lived” in a literal sense: it means that the cultural, axiological and metaphysical function that the concept of God once performed — grounding value, meaning, truth, morality — can no longer be sustained. Christianity dissolved itself by the very demand for truthfulness it had cultivated: science, critical history, modern philosophy, in seeking truth, discovered that the foundation they claimed to serve was human, all too human.

The death of God, for Nietzsche, is not the victory of atheism — it is the beginning of a task: to think beyond nihilism, to create new values, to bear the vertigo of a world without ultimate guarantees.

3.4 Heidegger and the critique of onto-theology

Martin Heidegger (1889–1976) took the critique to another level. In Identity and Difference (1957) and in lectures on Nietzsche, he formulated the thesis that all Western metaphysics, from Aristotle to Hegel, is onto-theo-logy: it thinks being from the supreme being, and the supreme being from being. God, in metaphysics, is introduced as causa sui (cause of itself) — the ultimate ground of the totality of beings.

But, Heidegger observes, “before such a God man can neither pray nor sacrifice. Before the causa sui, man can neither fall to his knees in awe nor can he play music and dance before this God” (Identity and Difference, GA 11). The God of onto-theology is a conceptual construct serving the metaphysics of ground — not the living God, not God as God.

Heidegger’s critique converges unexpectedly with the mystical tradition (Meister Eckhart, c. 1260–1328) and with apophatic theology (Pseudo-Dionysius, 5th–6th century): God, properly speaking, is not a being — not even the supreme one. The language of “being” and “existence,” applied to God, must be submitted to a radical negation (via negativa).

3.5 Pascal: the God of the philosophers and the God of Abraham

Heidegger’s insight had been anticipated, in a religious key, by Blaise Pascal (1623–1662). In the Mémorial (23 November 1654) — a fragment found, after his death, sewn into his coat — Pascal wrote:

“FEU. Dieu d’Abraham, Dieu d’Isaac, Dieu de Jacob, non des philosophes et des savants.” (“FIRE. God of Abraham, God of Isaac, God of Jacob, not of the philosophers and the learned.”)

The phrase sums up an abyss: the God one reaches through philosophical reason — First Mover, Necessary Being, causa sui — does not coincide, at least not immediately, with the God of personal faith, of revelation, of relation. The question, inherited by Pascal and radicalized by Heidegger, is whether philosophy, with its own instruments, is capable of thinking God as God, or whether it inevitably reduces Him to a piece of its system.

4. Contemporary rehabilitations

Despite the critiques, natural theology has not disappeared. In the 20th and 21st centuries, especially in the analytic Anglo-American tradition, it has received sophisticated reformulations.

4.1 Gödel’s ontological proof

Kurt Gödel (1906–1978) left, in manuscripts published posthumously in 1987, a modal formalization of the ontological argument in second-order logic. The proof, in brief, starts from axioms about “positive properties” (in an axiological sense) and deduces that there necessarily exists a being possessing all positive properties. Gödel’s formalization has since been the object of intense logical analysis, with refinements and critiques (notably by C. Anthony Anderson, Petr Hájek and others).

4.2 Alvin Plantinga: modal argument and reformed epistemology

Alvin Plantinga (b. 1932), in The Nature of Necessity (1974) and God, Freedom, and Evil (1974), formulated a modal version of the ontological argument:

• It is possible that there exists a maximally excellent being (one possessing omnipotence, omniscience and perfect goodness in every possible world).
• If it is possible that such a being exists, then in some possible world it exists.
• But maximal excellence implies existence in every possible world.
• Therefore the being exists in the actual world.

Plantinga acknowledges that the argument does not compel acceptance: it shows only that to accept the possibility of God’s existence is rationally to imply His actual existence. Whoever denies the conclusion must deny the possibility — which is no trivial matter.

In parallel, Plantinga developed reformed epistemology (Warranted Christian Belief, 2000): belief in God may be “properly basic” — rationally justified without need of arguments, just as belief in other minds or in the external world is.

4.3 Richard Swinburne: Bayesian probability

Richard Swinburne (b. 1934), in The Existence of God (1979; 2nd ed. 2004), abandoned the claim to demonstrative proof and proposed a cumulative and probabilistic approach: taken together, the various arguments (cosmological, teleological, from religious testimony, from consciousness, from religious experience) render the existence of God more probable than its non-existence. Bayesian calculus is the methodological instrument: each individual argument raises, to some degree, the prior probability of the theistic hypothesis.

5. The right question: does God exist or is God?

Having gathered arguments and critiques, we return to the initial question — now charged with new density. Does God exist? If “to exist” means “to be one thing among others,” the answer of the great metaphysical tradition is, paradoxically, no. God is not one thing among others. God is not the greatest of beings, even if infinite; God is the act by which any being is.

This is Aquinas’s reading. It is also, in a phenomenological key, Heidegger’s when he rejects onto-theology. It is the reading of Christian mysticism (Eckhart, John of the Cross), of apophatic theology (Pseudo-Dionysius, Gregory of Nyssa), and — in a distinct register — of the Neoplatonic metaphysics of the One in Plotinus (Enneads V and VI), in which the supreme principle lies beyond being (epekeina tês ousias, an expression Plotinus takes from Plato, Republic VI, 509b).

The question “Does God exist?” can therefore be displaced toward a more radical one: Is God? Not in the sense of belonging to the genus of beings, but in the sense of coinciding with the very act of being. This reformulation:

• Preserves transcendence: God is not alongside things, nor above them on the same plane; He is on another ontological register.
• Allows for negative theology: whatever we say of God is said by analogy; no concept exhausts Him.
• Recovers religious experience: the God to whom one prays, whom one loves or contests, is not a scientific hypothesis but the ultimate horizon of meaning — that in which we live and move and have our being (Acts 17:28).

Contemporary philosophy of religion oscillates between these positions. Some authors — especially in the analytic tradition — maintain that the traditional question (does God exist or not?) is legitimate and admits of argumentative answer. Others — in the wake of Heidegger, of Jean-Luc Marion (God Without Being, 1982), of Emmanuel Levinas (Totality and Infinity, 1961) — hold that to think God starting from the category “existence” is already to falsify Him. The question remains open, and perhaps it belongs to the very nature of the theological-philosophical problem that it should be so.

6. Conclusion

The question “Does God exist?” seems simple; it reveals itself, on analysis, as one of the most complex in philosophy. It traverses a field where metaphysics, modal logic, philosophy of religion, phenomenology, biblical hermeneutics and mystical theology converge. There is no consensual answer — and perhaps there never has been, even in periods of religious cultural hegemony.

What the philosophical tradition offers, however, is a series of rigorous distinctions that prevent the question from being answered too quickly:

• Distinguishing existere (existing as a being) from esse (being as act).
• Distinguishing demonstrative proof, inductive probability and basic belief.
• Distinguishing the God of the philosophers from the God of revelation, without necessarily opposing them.
• Distinguishing the critique of onto-theology from the denial of God.

Philosophy, in this domain, does not conclude — it purifies. It purifies the concept, exposes the limits of what can be said, shows where the silence of apophasis or the leap of faith takes the place of argument. And it may be precisely on this frontier — between what reason reaches and what it merely indicates — that the ultimate meaning of the question is decided: not so much whether God exists, but whether God is — and what it means, for us, to ask it.

Essential reading

• Anselm of Canterbury, Proslogion (1077–1078), especially chs. 2–4.
• Thomas Aquinas, Summa Theologiae I, q.2, a.3 (the Five Ways) and qq.3–4 (divine simplicity and perfection); De ente et essentia, ch. 4.
• Descartes, Meditations on First Philosophy (1641), Fifth Meditation.
• Leibniz, Monadology (1714), §§32–39; Theodicy (1710).
• Hume, Dialogues Concerning Natural Religion (publ. posth., 1779).
• Kant, Critique of Pure Reason (1781/1787), B620–B630; Critique of Practical Reason (1788), Dialectic, Book II.
• Pascal, Pensées and Mémorial (posthumous).
• Nietzsche, The Gay Science (1882), §125.
• Heidegger, Identity and Difference (1957); What Is Metaphysics? (1929).
• Étienne Gilson, Le Thomisme (1st ed. 1919; 6th ed. 1965); L’Esprit de la philosophie médiévale (1932).
• Alvin Plantinga, The Nature of Necessity (1974); Warranted Christian Belief (2000).
• Richard Swinburne, The Existence of God (1979; 2nd ed. 2004).
• Jean-Luc Marion, God Without Being (Dieu sans l’être, 1982).

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