The word "theology" is derived from the Greek theos and logos: "discourse about God." Hence, it has come to mean "knowledge about God" or "science of God." "Natural theology" or "philosophical theology" is the knowledge of God reached through human reason on its own resources; namely, through sense perception, understanding, and inference, which together yield evidence that is in principle accessible to all, independent of revelation. "Sacred theology" or "revealed theology," by contrast, is knowledge of God based principally on what he is believed to have disclosed to us about himself through word and deed, which the theologian is believed to accept only through the supernatural help of grace. "Theology" without further qualification, then, normally refers to our best available knowledge of God, therefore to the discipline that uses philosophy but that is principally based on the testimony of God himself.
Many conclusions of natural theology are believed also to have been revealed, such as that a God exists and that there is only one God. Similarly, many arguments of natural theology are used within theology. The clearest difference between the two disciplines is that an argument from the authority of revelation is at best a plausible argument within natural theology. But in sacred theology revelation is the best evidence possible, and philosophical argument plays only an auxiliary role. Vatican Council I affirms that sacred theology involves an order of knowing that differs from that of natural reason in both principles and object (Dei Filius 4).
Vatican I and Thomas Aquinas. Vatican I follows Aquinas's account, which employs the logic and scientific method of Aristotle's Analytics. On this account, demonstrative or scientific knowledge consists in a conclusion affirming a predicate, P, of some subject, S, through a middle term, M, which, in the ideal case, is the cause of P's belonging to S. Humans (S) can be known to be the only animals capable of humor (P) when it is understood that they are alone capable of understanding and reason (M). The subsequent causal knowledge of SP can be laid out for logical accuracy in a syllogism in which the conclusion is seen to follow through major and minor premises, that is, through principles that respectively contain P and S. Each scientific conclusion must be inferred immediately or ultimately from principles that are per se known or that are evident in perception. "Science" in a more general sense refers to the ordered set of conclusions regarding a unified subject-genus, which conclusions are derived from axioms common to all sciences as well as from principles proper to the subjectgenus. metaphysics, the most general of the sciences, for example, proves properties of any being whatsoever, whether material or immaterial, through axioms true of all beings. One of its goals is to arrive through proof at the first efficient and final causes of all beings, and to infer from these grounds the nature of the highest beings.
Aquinas argues that theology too is a science in the Aristotelian sense: its subject-genus is God, and its first principles are the truths of revelation, summarized in the articles of the Christian Creeds (Summa theologiae, I.1–8). These principles, although mysteries to us, are per se known to God as part of his own self-understanding. Just as both biology and physics may look at the same thing through different principles, the latter through principles drawn partly from a prior science of mathematics, so theology and natural theology both draw conclusions about God. But theology relies on principles drawn from another, higher science, to which it is subalternated: namely, God's science of himself. As a result, the proper object of theology—God and things related to God considered precisely as revelabile—is different from that of natural theology. The central themes of Christian theology are the Trinity and Incarnation, which cannot be proved or completely understood through reason but which have their own inner logic and can be rationally examined given faith in revelation.
From the above, it may appear that natural theology like theology is a science in its own right. For practical purposes it is normally treated and taught as an independent discipline. Yet for Aquinas, natural theology is but a material part of the science of metaphysics. God is not a subject that can be studied directly as can an object of perception like a flower or a bear. Instead, God's very existence must be proved, and this is possible for Aquinas only by examining beings as effects that require a concurrent cause. God enters metaphysics not as its subject but as the cause of its subject, being in general. Furthermore, God's nature is known only negatively by ascribing to the first cause of being certain pure perfections of beings, such as goodness and wisdom, while denying systematically our imperfect ways of knowing these perfections. Still, natural theology like theology must examine not only God in himself, however indirectly, but also all other beings as related to God, their author and end.
The subsequent knowledge of a God, although indirect, can be certain and necessary, as Aristotle would want and as faith itself holds. According to vatican council i, expressly citing Rom 1:20, by the light of natural reason it is possible to know with certainty, from created things, that God is the principle and end of all. For Aquinas, such knowledge also provides crucial preparation for the acceptance of faith, just as nature provides a foundation to be perfected by grace (Summa Theologia, I.2.2 ad 1). For him faith is not a mere blind leap into darkness. With the tradition he takes natural theology to establish, not the articles of the Creed, but its pream bles, such as the existence of God and the end of human life. Nature and grace, reason and revelation have God as their author and so cannot truly contradict each other. Should the natural theology of the philosophers contradict revelation, insists Thomas, one may be sure that an error in reasoning has been committed.
History. The founder of natural theology in the West is often taken to be the fifth-century b.c. Ionian Presocratic thinker Xenophanes. He criticized the anthropomorphism of the Greek myths and affirmed one divine being as an unchanged, simple, and intelligent principle of natural events. Plato's critique of Homer and the poets in Republic 2 culminates the early Greek tradition, and Plato speaks there of a "theologia" that is needed as a corrective to mythologizing (379B). Although Aristotle uses the term theologia of the poets or "theologians," he also calls his own First Philosophy or metaphysics "theological science" insofar as it treats the first principles and causes of things (Metaphysics E.1). Plato and Aristotle each offer proofs of the gods of their cosmologies and reflect upon the nature and attributes of first beings. In the fifth century a.d., Proclus's Elements of Theology systematizes the philosophical theology of Plotinus, the greatest pagan sage after Plato and Aristotle.
Natural theology has been practiced in various ways since the Greeks, under the inspiration of different philosophies, and with varying degrees of consciousness of and confidence in reason operating under its own principles. Only in stages did the project come to be seen as compatible with Christianity. Within Catholicism, complete fideism, such as Tertullian expressed, soon became no longer viable, but as harsh a critic of reason as Peter Damian is today a doctor of the Church. And outside of Catholicism, leading modern thinkers such as Karl Barth and Alvin Plantinga continue at times to question deeply the entire project of natural theology.
The Eastern and Western Church Fathers employed Platonic and Neoplatonic modes of thought, as did such subsequent thinkers as Boethius, Pseudo-Dionysius, John of Damascus, and John Scotus Erigena. Philosophy was not sharply distinguished from theology in the tradition of "faith seeking reason" that began with Augustine and that culminated with Anselm's great confidence in reason and his ontological argument. Simultaneously natural theology was pursued just as forcefully but with different degrees of orthodox approval within Judaism—from Philo to Maimonides—and within Islam, in the kalam tradition, as well as among the great Arabic thinkers al-Farabi, al-Ghazali, Avicenna, and Averroes. These traditions converged to produce Western Scholasticism's increased sense of the autonomy of natural reason in the thirteenth century, as in Albert the Great and Aquinas, followed by the critical reactions of Bonaventure, John Duns Scotus, and William Ockham. Natural theology continued to form an integral part of the great rationalist systems of Descartes, Spinoza, and Leibniz. But these inevitably evoked the radical critiques of Hume and Kant, questioning the very possibility of metaphysics as a science, critiques that continue to haunt natural theology today. In the last century, deep skepticism regarding even the legitimacy of religious language marked the "philosophy of religion" in its positivist origins. Yet postmodern critiques of a "pure reason" independent of community and affectivity have helped make room for renewed discussion of theism in both Continental and Anglo-American approaches.
Terminology. "Natural theology" in our current sense is not found prior to the sixteenth century. Augustine distinguishes "natural" from "mythic" and "civic" theology, describing the former as the fruit of philosophical argument (City of God 6.5). Yet his threefold division appears to be Stoic in origin, and for him as for the Stoics, "natural theology" affirms material deities. Ever since Augustine, then, one finds criticisms of "natural theology" as worldly and idolatrous, criticisms voiced by, among others, Aquinas and Suárez. Suárez, however, also speaks of "natural theology" as synonymous with metaphysics, proceeding under our "natural light" (Metaphysical Disputations 1). In Francis Bacon "natural theology" is first seen as a separate discipline from general metaphysics (On the Dignity of the Sciences 3.1.2–3), a distinction rendered widespread by Christian Wolff. Leibniz introduced the term "theodicy," referring to a theological justification of God in the face of evil. Subsequently the term was often taken to be synonymous with natural theology. Finally, in the wake of Schleiermacher in nineteenth and early twentieth-century thought, "natural theology" takes on still a third sense, referring to an innate experience of the divine that is common to all humanity.
Bibliography: l. gerson, God and Greek Philosophy: Studies in the Early History of Natural Theology (New York 1990). h. a. wolfson, The Philosophy of the Church Fathers (Cambridge, Mass. 1956). j. owens, "Theodicy, Natural Theology and Metaphysics," Modern Schoolman 28 (1951) 126–137. h. davidson, Proofs for Eternity, Creation, and the Existence of God in Medieval Islamic and Jewish Philosophy (Oxford 1987). r. mcinerny, Being and Predication (Washington 1986). l. elders, The Philosophical Theology of St. Thomas Aquinas (New York 1990). j. wippel, Metaphysical Themes in Thomas Aquinas (Washington 1984). n. kretzmann, The Metaphysics of Theism: Aquinas's Natural Theology in Summa Contra Gentiles (Oxford 1997–1999). j. collins, God in Modern Philosophy (Chicago 1959).
[d. b. twetten]