Theology

Plato does not use the word "theology" in the later technical sense that distinguishes natural from sacred doctrine, yet he is among the first to insist that knowledge of divine things belongs to reason rather than to poetry or myth alone. In the Laws, Book X, the Athenian Stranger argues against those who deny the gods, those who hold that the gods take no care of human affairs, and those who suppose that the gods may be bribed by gifts. The soul, on this account, is prior to body, self-moving and immortal; the ordered motions of the heavens are offered as evidence of a supremely good soul that guides the cosmos. What is presented is philosophical argument about the divine within a religious context, not merely pious storytelling, and it may be taken as an early form of what later writers call natural theology.

The Timaeus extends the same inquiry into the origin and order of the world. A divine craftsman, the Demiurge, fashions the visible cosmos by looking to the eternal Forms as his model. He is good, and because he is good he wishes all things to resemble himself as far as possible. The cosmos is described as a living creature endowed with soul and reason, an image of the intelligible world made in time. Plato's account is theological in that it explains the world's existence and order by reference to a divine intelligence acting for the sake of the good. The same dialogue also touches questions of creation, soul, and the relation of time to eternity that reappear under the ideas of God, Soul, and World.

What Plato establishes, for those who follow him, is the conviction that philosophical reason can reach the divine, or at least certain truths about it. The gods, on this view, are not arbitrary powers to be appeased but rational beings whose goodness is the cause of cosmic order. Whether theology is therefore a branch of philosophy, and perhaps its highest branch, becomes a standing question. Aristotle will give the inquiry a formal place among the theoretical sciences, and Augustine will ask how near the Platonists come to Christian faith without the aid of revelation.

Plato leaves later tradition a systematic philosophical discourse about the divine, together with a problem of method and audience. If reason can reach the divine, it remains to be explained why he also insists that only the few, after long disciplined study, ever arrive. Aristotle will argue that the divine can be reached by reasoning from motion and causation, without the dialectical ascent of the Republic. The question of how far unaided reason goes, and where faith or revelation must begin, is treated more fully under the ideas of God, Religion, and Knowledge.

Aristotle gives theology a formal place in the architecture of knowledge. In the Metaphysics he distinguishes three theoretical sciences: physics studies things that move and exist separately; mathematics studies things that do not move but do not exist separately; and theology, or first philosophy, studies what is both immovable and separate from matter. Because its object is the highest kind of being, theology is the most honorable of the sciences. If the divine is present anywhere, he writes, it is present in things of this sort, and the most honorable science must deal with the most honorable genus. He also calls theology a divine science not because it is divinely inspired, but because, having the divine for its object, it is the science most meet for God to have, or for God above all others.

The culmination of this inquiry is the doctrine of the unmoved mover in Metaphysics XII. The eternal motion of the heavens requires an eternal cause that itself does not move. This first mover acts not by pushing or pulling but by being desired: it moves as the object of love moves the lover. Its activity is pure thought, and what it thinks is itself, for the highest thought must have the highest object. God, on this account, is thought thinking thought, an activity of perfect self-contemplation that is also perfect happiness. Aristotle dismisses the mythological "theologians" who thought only of what was plausible to them, and treats the legends of the gods as handed down for the persuasion of the multitude rather than as science.

Aristotle's theology is wholly philosophical. It proceeds by argument from observed facts about motion and causation to a conclusion about the highest being. There is no appeal to revelation, no prescription of prayer or worship, and no claim that the unmoved mover knows the world or concerns itself with human affairs. This purity of method is what later Christian and Jewish writers both use and revise. The problem of species, motion, and first cause is treated more fully under the ideas of Being, Cause, and God; here the point is that theology, for Aristotle, is the highest speculative science, not a sacred doctrine grounded in faith.

Aristotle establishes theology as a philosophical discipline with its own proper object and method. His unmoved mover, a God that neither knows the world nor cares for it, raises a question for every subsequent thinker who wishes to combine philosophical theology with a personal, providential God. Aquinas will argue that Aristotle's arguments from motion and causation remain valid as far as natural reason goes, while holding that revelation discloses truths about God that philosophy cannot demonstrate. The relation of natural theology to sacred doctrine thus becomes a central theme of the medieval discussion.

Augustine recasts the relation between philosophy and theology by treating faith as the guide of reason rather than its enemy. In the Confessions he describes how the books of the Platonists taught him to seek an immaterial God, yet left him unable to arrive. He could see the truth from a distance but could not reach it; only the humility of faith, accepting Christ as mediator, gave him the power to arrive. The formula is crede ut intelligas: believe in order that you may understand. Reason does not generate faith, on this view, but faith makes understanding possible. The same relation of belief and knowledge appears under the ideas of Knowledge and Religion.

In the City of God, Books VIII and XI, Augustine surveys pagan theology and finds the Platonists closest to the truth. They grasped that God is immaterial, eternal, and the source of all being. Yet without revelation, he holds, they could not know God as Trinity or understand creation from nothing, and they failed to worship him properly. Drawing on Varro, Augustine distinguishes three kinds of theology: the mythical theology of the poets, the civil theology of the state, and the natural theology of the philosophers. Only the last deserves serious consideration, and even it remains incomplete without Scripture. He will not refute every vain theological opinion of the philosophers, he says, but only those who, while agreeing that there is a divine nature concerned with human affairs, deny that the worship of the one unchangeable God is sufficient for blessedness.

Augustine clarifies the hierarchy between faith and reason in theological inquiry. Reason remains a working instrument: it can refute error, illuminate Scripture, and draw out the implications of revealed truth. It cannot, however, function as an independent tribunal that stands above revelation. The theologian begins with what God has disclosed and then uses every intellectual resource to understand it more deeply. Augustine also treats heresy and controversy as occasions that force the Church to investigate articles of faith more accurately and proclaim them more earnestly, a theme that returns in the medieval discussion of orthodoxy and the development of dogma.

Augustine's insistence that theology begins with faith and employs reason in faith's service defines much of medieval Christian thought in the Latin West. The question he leaves open, whether faith merely supplements reason or fundamentally redirects it, becomes a fault line for later writers. Aquinas will try to resolve it by arguing that natural theology and sacred doctrine are two distinct but cooperative sciences, neither absorbing the other. The problem of how far the light of nature can go without revelation is also taken up under the idea of God.

Aquinas draws a clear distinction between two kinds of theology. Natural theology is a branch of philosophy: it proves God's existence and certain divine attributes, such as unity, goodness, and immutability, by reasoning from the created world. Sacred theology, or sacra doctrina, starts from truths revealed by God in Scripture and develops their implications with the tools of logic and metaphysics. The first article of the Summa Theologica asks whether any doctrine beyond the philosophical sciences is necessary. Aquinas answers that it is, because human salvation requires truths that exceed the reach of natural reason, among them the Trinity and the Incarnation. Sciences, he adds, are differentiated according to the means through which knowledge is obtained; hence the theology included in sacred doctrine differs in kind from that theology which is part of philosophy.

Sacred theology is a true science, even though its first principles are not self-evident to us. Every science derives its principles from a higher science: optics borrows from geometry, music from arithmetic. Sacred theology borrows its principles from God's own knowledge, communicated through revelation. Because God cannot err, these principles are more certain than those of any merely human science. The theologian accepts revealed premises on faith and then reasons from them with full intellectual rigor. Propositions that can be demonstrated by reason, such as the existence of God, are not articles of faith but preambles to the articles; nothing prevents a man who cannot grasp a proof from accepting as a matter of faith something that is in itself capable of being scientifically known.

The relation between the two theologies is cooperative rather than competitive. Natural theology provides the preambles of faith, truths about God that reason can establish independently and that prepare the mind to receive revelation. Sacred theology presupposes and perfects these preambles, extending knowledge of God beyond what philosophy can attain. Grace does not destroy nature but perfects it; likewise, revealed theology does not cancel philosophical theology but completes it. Because sacred doctrine considers all things under the aspect of God, either as God himself or as referring to God as beginning and end, its subject matter ranges widely over creation, human acts, law, sin, grace, and the sacraments, a scope treated also under the ideas of God, Religion, and Virtue.

Aquinas gives the Western tradition its most systematic account of theology's nature and method. Later writers draw the line between reason and revelation differently. Montaigne will question whether natural reason is strong or constant enough to serve as theology's preamble; Bacon will limit natural theology to what refutes atheism without informing religion; Descartes will claim that certain truths about God and the soul can be demonstrated by natural reason alone. The Thomistic distinction between natural and sacred theology remains the framework against which these revisions are measured.

Montaigne's "Apology for Raymond Sebond" is the longest of the Essays and, despite its title, a sustained examination of the project it claims to defend. Sebond had argued that the truths of Christianity could be established by natural reason. Montaigne professes to support this claim, then catalogues the contradictions among philosophers, the errors of the senses, and the dependence of human judgment on custom, health, and temperament. If reason cannot settle whether the soul is mortal, whether the senses are reliable, or whether any philosophical system is true, he asks, how can it presume to demonstrate the existence and nature of God? The question belongs as much to the critique of knowledge as to theology.

The strategy is often called fideist, though interpreters differ on how far Montaigne intends a defense of faith. By undercutting the pretensions of natural theology, he leaves knowledge of God to disclosure through grace and faith rather than through syllogisms. He observes how short the firmest maintainers of the immortality of the soul fall when they try to prove it by human reason, and he concludes that God alone has dictated it, and faith; it is no lesson of nature and our own reason. The denial of God's existence is, he thinks, unnatural and hard to establish; yet the affirmation is no less beyond reason's power to establish with certitude, for all things produced by our reasoning are subject to incertitude and controversy.

Montaigne does not attack theology itself, only the philosophical ambition to construct it from below. He is willing to submit to the teachings of the Church; what he refuses is the claim that these teachings can be reached or confirmed by unaided reason. His skepticism is directed at the pretensions of human intellect, not at the reality of God. In this he differs both from Aquinas, who assigns certain truths to natural theology as demonstrable without faith, and from later philosophers such as Descartes, who hold that we can know God by reason with more certainty than we know most other things. The problem of faith and reason is treated more fully under the ideas of Religion and Knowledge.

Montaigne's critique of natural theology opens a line of argument that later writers will develop in different directions. His insistence that reason cannot reach God with certitude anticipates both Pascal's distinction between the God of the philosophers and the God of Abraham, and Hume's more thoroughgoing examination of the arguments from design and causation. After Montaigne, defenders of rational theology must answer the charge that their instrument is too feeble for the task it claims to perform.

Francis Bacon approaches theology with a reformer's concern to keep the domains of knowledge clearly separated. In The Advancement of Learning he divides knowledge into three great branches corresponding to the three faculties of the mind: history (memory), poetry (imagination), and philosophy (reason). Theology belongs partly to philosophy and partly to a separate domain of inspired or revealed knowledge. Natural theology, or divine philosophy, is that knowledge of God which may be obtained by the contemplation of his creatures. It is divine in respect of the object and natural in respect of the light. Its bounds, Bacon says, are that it suffices to convince atheism, but not to inform religion.

Bacon is emphatic that natural theology cannot yield a religion. The contemplation of nature, its order and regularity, may demonstrate a divine power. It cannot tell us whether God desires worship, what form that worship should take, or what God has promised to those who obey him. These things are known only through revelation. Inspired or sacred theology is grounded only upon the word and oracle of God, not upon the light of nature. Any attempt to extract points of faith from natural reason produces, on his view, heretical religion and imaginary philosophy. He would limit natural theology to what can be drawn from nature, and he excludes attempts to induce from nature any verity or persuasion concerning the points of faith, though he grants that natural as well as divine theology may treat of the nature of angels and spirits as neither inscrutable nor interdicted.

This partition reflects Bacon's broader project of reforming the sciences. Each discipline is to work within its proper limits and by its proper method. Natural philosophy proceeds by induction from experiment; theology proceeds from the word of God accepted on faith. Mixing the two corrupts both. The philosopher who reads theological conclusions into nature produces bad science; the theologian who builds doctrine on philosophical arguments produces fragile faith. Under the head of divinity Bacon also divides the subject matter of sacred theology into matter of belief and matter of service and adoration, deriving four main branches: faith, manners, liturgy, and government. The question of method in the sciences is treated more fully under the ideas of Knowledge and Science.

Bacon's separation of natural theology from revealed religion shapes much early modern discussion of the bounds of reason in divinity. He also deplores the unprofitable subtlety and fruitless controversy that arise when religion and philosophy are commixed. Yet the boundary he draws remains open to different uses. If natural reason can establish that God exists, later writers may press further and claim, as Descartes does, that reason can also demonstrate God's veracity and thereby underwrite certain knowledge. Whether that extension is legitimate, or whether Bacon's caution forbids it, is a standing dispute in the period that follows.

Descartes revives the project of proving certain truths about God by natural reason, but on foundations different from those of medieval natural theology. Where Aquinas argued from the world to God, Descartes argues from the mind's own contents. He reserves the word "theology" largely for sacred doctrine, and treats what others call natural theology as a part of metaphysics or philosophy. Dedicating his Meditations to the faculty of theology at Paris, he notes that theologians affirm both that the existence of God may be proved by the natural reason and that knowledge of Him is clearer than that of many created things. He has always considered, he writes, that the two questions respecting God and the soul were the chief of those that ought to be demonstrated by philosophical rather than theological argument, if infidels are to be persuaded.

In Meditation III he discovers within himself the idea of a supremely perfect, infinite being. This idea, he argues, could not have been produced by a finite mind; it must have been placed in him by an actually existing infinite being. The cause of an idea must contain at least as much reality as the idea represents, and since the idea of God represents infinite perfection, only God himself could be its cause. In Meditation V he offers a second proof, a version of the ontological argument. Just as the idea of a triangle necessarily includes the property that its angles sum to two right angles, the idea of a supremely perfect being necessarily includes existence. A being that lacked existence would lack a perfection and so would not be supremely perfect. Therefore God exists, and this truth is as certain as any theorem of geometry.

Descartes also confesses the limitations of the mere philosopher's knowledge of God. God cannot be comprehended by the human mind in his entirety; clear and distinct knowledge applies only to that finite cognition which is proportionate to our capacity. Fewer persons are fitted for metaphysical speculation than for geometry. Yet within those limits he claims demonstrative certainty. God, in turn, guarantees the reliability of clear and distinct perception, underwriting the Cartesian system of knowledge. Theology, so far as it is pursued by natural reason, is not a separate discipline requiring faith for its first principles; it is the rational foundation on which other knowledge rests. The proofs of God's existence are treated more fully under the idea of God; here the point is Descartes' conception of the relation between philosophy and sacred doctrine.

Descartes makes the demonstration of God by natural reason central to modern philosophy. Because his proofs claim mathematical certainty, they become primary targets for later criticism, first in Hume's examination of design, causation, and the ontological argument, and then in Kant's critique of speculative theology. The fate of Cartesian natural theology defines much of the Enlightenment debate over what reason can and cannot establish about the divine.

Hume subjects natural theology to a sustained critique. The Dialogues Concerning Natural Religion, published posthumously, examines the principal arguments for God's existence and finds each of them wanting. The design argument, which infers an intelligent creator from the order of nature, receives the most extended treatment. Through the character Philo, Hume observes that the analogy between human artifacts and the cosmos is weak. We have experience of watchmakers but none of universe-makers. The world's order might be explained by material principles, by many gods, or by chance; a single, infinitely perfect designer is only one hypothesis among many, and not clearly the most probable. The problem of analogical reasoning from experience is also discussed under the ideas of Knowledge and Experience.

The cosmological argument fares no better on his account. Hume denies that we can reason from the existence of individual things to a necessary first cause of the whole. Each part of an infinite causal chain may be explained by the part before it; to demand an explanation for the chain as a whole may be to ask a question that has no answer. The ontological argument is dismissed more briefly on the grounds that existence is not a predicate: we cannot define things into being, no matter how perfect we conceive them. These objections bear on Descartes and the Scholastic proofs, and on any natural theology that claims to establish the nature of God from reason or experience alone.

In the Enquiry Concerning Human Understanding, Hume extends the critique to miracles and particular providence. No testimony for a miracle can establish it as probable, he argues, because the uniform experience of natural law always outweighs the reports of witnesses. Even if we grant a creator of some kind, we have no basis for inferring that this creator is good, concerned with human affairs, or willing to reward or punish. Natural theology, stripped of its pretensions, reduces to one vague proposition: the causes of order in the universe bear some remote analogy to human intelligence. Nothing more, on his view, can be said with warrant. The relation of this conclusion to moral and religious life is taken up under the ideas of Religion and God.

Hume's critique effectively closes, for many later readers, the classical project of natural theology as a demonstrative science. Philosophers who wish to maintain a rational case for God's existence must either answer his objections directly or, as Kant will do, relocate the grounds of theological conviction from speculative reason to practical morality. The distinction between what experience can show and what faith or moral postulation may still require remains central to the modern discussion of theology's nature and limits.

Kant agrees with Hume that speculative theology fails, but he offers a different diagnosis of why it fails and a different account of what remains. Theology, he holds, is based either on reason alone (theologia rationalis) or upon revelation (theologia revelata). Within rational theology he further distinguishes transcendental theology from natural theology according to the method which reason employs, and he differentiates between speculative and moral theology as works of pure theoretic and pure practical reason. In the "Transcendental Dialectic" of the Critique of Pure Reason, he argues that reason naturally generates the idea of God as the ideal of pure reason, the concept of a being that contains all reality. This idea is not a product of experience but a necessary structure of thought. The trouble is that reason then tries to prove that this ideal actually exists, and every such proof is invalid.

Kant identifies three possible proofs and rejects each in turn. The ontological argument fails because existence is not a real predicate; saying that God exists adds nothing to the concept of God but only posits the subject itself. The cosmological argument smuggles in the ontological argument by assuming that a necessary being must be the most real being. The physico-theological, or design, argument, while psychologically compelling, can at best establish a very powerful architect of the world, not an omnipotent creator from nothing; and it too ultimately depends on the ontological argument to close the gap between a designer and the God of traditional theology. All attempts of reason to establish a theology by the aid of speculation alone are fruitless; a rational theology can have no existence unless it is founded upon the laws of morality.

Having set aside speculative theology, Kant rebuilds theology on moral foundations. In the Critique of Practical Reason he argues that the moral law commands us to seek the highest good: a state in which virtue is perfectly proportioned to happiness. Since nature does not guarantee this proportion, and since the moral law cannot command the impossible, we must postulate the existence of God as the being who can ensure that virtue is ultimately rewarded. God is not an object of theoretical knowledge but a practical postulate, a necessary presupposition of the moral life. The moral argument is not intended to supply an objectively valid proof of God's existence for the skeptic; it is meant to show that one must adopt the assumption as a maxim of practical reason if one wishes to think consistently with morality. The relation of this moral theology to freedom, immortality, and the highest good is treated more fully under the ideas of Duty, Happiness, and God.

Kant revises the classification of theology for the modern period. Speculative theology is declared incapable of demonstration; moral theology takes its place as the only rational theology that remains. His distinction between what we can know and what we must postulate for the sake of the moral law, between the theoretical and the practical use of reason, sets the terms for subsequent attempts to relate philosophy and religion. Whether moral theology is continuous with sacred doctrine, or only a philosophical substitute for it, remains a question for those who write after him.