Several renowned Augustine interpreters hold that Augustine developed a notion of rationality based precisely on the unification of reason and revelation. Étienne Gilson, for example, writes in his Introduction à l’étude de Saint Augustin: “One never knows if Augustine speaks as a philosopher or a theologian.”1 Rowan Williams claims that for Augustine not even self-knowledge, as expressed in his proto-Cartesian formula “si enim fallor, sum,” is possible without the mediation of God’s revelation: “There is nothing that can be said of the mind’s relation to itself without the mediation of the revelation of God as its creator and lover. At the heart of our self-awareness is the awareness of the self-imparting of God.”2 Williams judges the unification of philosophy and revelation to be a particular achievement of Augustine’s, in contrast to which the modern isolation of reason from faith represents a regression.3 Even Alvin Plantinga praises Augustine for that concept of rationality which—in contrast to the Thomistic tradition—joins philosophy and faith in order to exhaust all sources of knowledge available to us.
In what follows, I will argue against the thesis that Augustine laid out a unified science in which reason and faith merge. In my opinion, Augustine frames the relationship between philosophy and revelation as a well-differentiated coordination of independent parts. Augustine argues first that philosophy is insufficient for salvation, second that philosophy is not even necessary because faith suffices for redemption, and third that philosophy is still valuable since it is helpful in supporting and clarifying Christian faith.
Augustine entertains a notion of philosophy as an endeavour of autonomous reason. For Augustine the whole of metaphysics, including the proof of God’s existence, is a work of reason alone, as is epistemology and ethics. As Augustine reports, all of this was already taught accurately by Plato—and that means without the support of revelation.4 Augustine states that Plato found in God “the cause of being, the principle of reason and the rule of life,”5 and he credits the pagan philosopher with rightly maintaining “that the wise man is the man who imitates, knows and loves [this] God, and that participation in [this] God brings man happiness.”6 Most of Augustine’s metaphysics is derived from Plato and Neoplatonism: the immateriality of God and the human soul; unity, truth and goodness as transcendental determinations of being; and evil as a deprivation of good are just several of the metaphysical theses Augustine inherits from Plotinus and Porphyry. In the realm of practical philosophy, he adopts the doctrines of the purposefulness of all action, of God as the final goal and highest good for humans and of virtue as the necessary means to that goal.
To some extent, Augustine even adopts the Platonic notion of belief in authority as a necessary preparation of knowledge. In De ordine, for example, Augustine asserts: “With respect to time, authority comes first, but in the order of reality reason is prior.”7 Authority comes first, because human beings are so trapped in their false orientation that any attempt to lead them directly to understanding fails. One may also think of Plato’s cave allegory, in which the one climbing toward the light must first be persuaded and even compelled to turn away from the shadows and ascend to true reality. The will and ability to gain insight must first be produced, and, according to Plato and Augustine, authority achieves this. Through its call, authority induces human beings to take up the way of understanding. Augustine sees this as the task of rhetoric: it drives human beings on, it is “full of seductive stimuli, which it displays to the people in order to lead them to the end most useful to them.”8
At some point, however, human beings should outgrow the “cradle of authority,” as Augustine says,9 and turn toward reason and insight. Some of the Bible passages cited most frequently by Augustine should be understood in this sense, for example Isaiah 7:9, “If you do not believe, you will not understand” (nisi credideritis, non intellegetis) and Matthew 7:7, “Search, and you will find.”10 Belief in authority prepares for understanding, search motivated by belief leads to knowledge. This preparation, however, is merely pedagogical, just like in Plato’s allegory. Belief in this sense does not ground understanding. On the contrary, understanding, once it is reached, supports itself with its own evidence, which allows it to leave the preparatory method of belief behind. The course of the conversation in De libero arbitrio makes the transitory character of belief in authority very clear. Again and again Evodius, Augustine’s interlocutor, proposes a thesis, to which Augustine responds, “Do you know for sure what you say, or do you only believe it based on authority?” Evodius willingly confesses that he has spoken out of belief in authority,11 with the result that Augustine invariably leads him to the evidence of insight, which no longer needs to be grounded on belief.
In Confessions I–VII Augustine confirms this concept of the relationship between understanding and belief in terms of his own life path. As a child Augustine had been brought up in the Catholic faith by his mother Monica, and even during his restless youth, he never gave this faith up. His intellectual escapades—his enthusiasm for Cicero and his Manichaeism and Neoplatonism—were basically just paths on which Augustine the believer hoped to find understanding.12 For Augustine, Neoplatonism represents the most important philosophical movement, because with its help he was first able to implement the program of transforming belief in authority into understanding. Furthermore, the Platonic philosophers introduced Augustine to the well-known schema of the movement toward God: turning away from the external world, turning inward into oneself, ascending upward to transcendence beyond the ego. Even Augustine’s accounts of his intellectual ascents to God are clearly modelled after similar reports by the pagan philosopher Plotinus.13 The encounter with Neoplatonist philosophy enabled Augustine himself to outgrow the “cradle of authority,” i.e., to substitute knowledge for belief.
For Augustine, Platonic philosophy does provide insight, but insight alone is not wisdom, nor does it enable us to lead a happy life. The second half of Confessions VII and book VIII are designed to show that autonomous reason, although perfectly legitimate in itself, is unable to let us reach the ultimate goal of life. As Augustine says, the Platonists glimpse “from a wooded summit the homeland of peace,”14 and even know that virtue is the path to this homeland. But they do not know how one reaches this path and actually becomes virtuous, so that instead of only seeing the homeland from a distance one is actually capable of inhabiting the homeland.15 For Augustine, reaching the goal and holding on to what is seen requires faith in Jesus Christ.
According to Augustine, Christian faith comes into play with the question: Can human beings make what they objectively recognize as the highest being into what they subjectively strive for as their supreme goal? The question that induces faith is not “what is the highest good?” or “what is virtue?” but “how can we obtain the highest good?” or “how do we become virtuous?” Augustine believes that without the grace of God that comes from faith in Jesus Christ, human beings can indeed recognize what the good is, but do not have the strength to do good. Here philosophy hits its limit. For Augustine, philosophy is able to instruct, but not to convert us to a life of virtue.
Augustine explains this view in several places in his work, most impressively in his Tractates on the Gospel of John.16 In these tractates, he explicates the relationship of philosophy and Christian faith by assuming, modifying and augmenting Plato’s image of ascent.17 According to Augustine, we do not have to rise up from a cave into the light of day as Plato imagines; rather, we have to scale a mountain from the plains. Just as Plato’s cave person beholds the sun from the earth’s surface, Augustine’s mountain climber sees the truth, the goal of life and the homeland he wants to arrive at from the mountain peak. But for Augustine this homeland is not reached by sight alone. It lies in the distance and is only glimpsed from afar, for between the mountain summit and the homeland there is a sea that must be overcome—the sea of life. The means of passage is a ship constructed of wood, namely the wood of the cross. It is only aboard this ship that humans can cross the sea and truly reach the homeland glimpsed from the mountain peak.
Augustine’s image is readily deciphered. The view from the mountain peak represents the noetic vision of the highest good as Plato describes it in the allegory of the cave and in his divided line analogy. By extending this image with the element of the sea, however, Augustine makes his reservation against Platonic noesis apparent. The metaphysical vision of God does not entail that one has reached the goal, he argues; rather this vision is merely a contemplation from afar. Augustine therefore draws a distinction between the sight of God and abiding with him, between intellectual vision and willed adhesion to God, between the glimpse of the highest good and the ability to hold fast to the summum bonum.18 Augustine acknowledges that Platonic philosophy does attain to such a vision, but he does not believe that it enacts a sustained conversion of the will, away from the orientation towards finite goods to a focus on God as the highest good. Philosophy is capable of teaching up to the noetic vision, but it is incapable of converting. Conversion occurs only through the grace of God, which presupposes faith in Jesus Christ. Augustine’s expansion of the cave allegory with the parable of the mountain and the sea demonstrates his esteem for the theoretical competence of Platonic philosophy but also his denial of its therapeutic competence, which he attributes to religion.
Augustine further elaborates his depiction by distinguishing three types of humans: the great ones, the little ones and the proud ones. Of the great ones he writes, “It is good . . . and best of all, if it be possible, that we both see whither we ought to go, and hold fast that which carries us as we go. This they were able to do, the great minds . . . they were able to do this, and saw that which is. For John, seeing, said, ‘In the beginning was the Word, and the Word was with God, and the Word was God.’ They saw this, and in order that they might arrive at that which they saw from afar, they did not depart from the cross of Christ, and did not despise Christ’s lowliness.”19 The great humans—and Augustine obviously counts the evangelist John among them—can see; they dispose of the noetic vision of the divine, and simultaneously they trust in the cross in order to traverse the sea and arrive at the envisioned reality. Through philosophy they possess the highest form of knowledge, and through religion their will is entirely oriented towards God. To philosophize and to believe, to see the good itself and to love it above everything else, this is the best way to live according to Augustine.
Of the little ones he writes, “But little ones who cannot understand this, who do not depart from the cross and passion and resurrection of Christ, are conducted in that same ship to that which they do not see, in which they also arrive who do see.”20 Philosophical training, culminating in the visio intellectualis of the Platonists, is therefore desirable, according to Augustine, but it is not necessarily required in order to arrive at the goal. For those who cannot see also reach the longed-for homeland, if they simply board the ship of faith and trust that it will bring them to the desired place.
Augustine clarifies this point in Confessions VII. Comparing the Platonic writings with the Gospel of St. John, he finds the two overlap: “There [in the Neoplatonists] I read, not of course in these words, but with entirely the same sense and supported by numerous and varied reasons, ‘In the beginning was the Word and the Word was with God,’”21 and so forth. Neoplatonist metaphysics and the Gospel thematically coincide. The coinciding, however, is only partial. It pertains just as far as the Gospel teaches metaphysical truths. Within this partial overlap of contents, Augustine notes a difference in method. Scripture bears these truths as a matter of faith, while philosophy presents the same truths in the mode of reason and insight (“supported by numerous and varied reasons”). If the metaphysical truths about God are taught not only by the philosophers but also by Holy Scripture, and if they need not be intellectually grasped but can be held by faith instead, then philosophizing is simply not necessary to adopt the right views about God. According to Augustine, belief in metaphysical truths can be overtaken by insight, and intellectuals like Augustine himself will certainly strive for knowledge as far as knowledge goes. Still, for those with lesser mental abilities, i.e., for those with weak (mental) eyes, belief in the authority of Scripture suffices even where Scripture advances metaphysical theses.
For Augustine, those who have the intellectual power to do so should philosophize, but the simple believer will suffer no harm from not doing philosophy. On the contrary, the learned are in danger of taking pride in their knowledge and thus of losing God’s grace. According to Augustine’s autobiography, he himself was at risk of glorying in his education even after his conversion. In his Cassiciacum dialogues, Augustine does think that even if dialectic and the liberal arts cannot lead to happiness, they are still necessary to reach the goal of life. The Confessions, however, back away from this view, denouncing it as an expression of the pride of the school.22 And the Retractations say that many of the saints knew nothing about the liberal arts, and many of the learned were no saints.23 Those saints reached happiness without philosophy, i.e., just by faith. For Augustine, philosophy is not necessary for salvation.
Augustine thus rejects the elitism of antiquity, which allows only the few who have access to the good of education a chance at happiness. From a Christian point of view, this possibility is open to all, even to those who due to a lack of philosophical training cannot attain a vision of the eternal, but who faithfully appropriate the teachings of God through trust in the authority of Holy Scripture. This is what Augustine means when he writes, “For no one is able to cross the sea of this world, unless borne by the cross of Christ. Even he who is of weak eyesight sometimes embraces this cross; and he who does not see from afar whither he goes, let him not depart from it, and it will carry him over.”24
Augustine allots the pagan Neoplatonists to the third type of human, the proud ones. What Paul says in the epistle to the Romans applies to them: “Professing themselves to be wise, they became fools” (1:22). Their foolishness does not consist in not knowing God, Augustine claims, but in the fact that they saw him and still could not summon the humility to recognize the son of God become human in Jesus Christ. Augustine writes, “Those, therefore, concerning whom he said, ‘who, when they had known God,’ saw this which John says, that ‘by the Word of God all things were made.’ For these things are also found in the books of the philosophers; and that God has an only-begotten Son, by whom are all things. They were able to see that which is, but they saw it from afar: they were unwilling to hold the lowliness of Christ, in which ship they might have arrived in safety at that which they were able to see from afar, and the cross of Christ appeared vile to them. The sea has to be crossed, and do you despise the wood? Oh, proud wisdom!”25
Augustine links the pride of the Neoplatonists to their refusal to accept the doctrine of incarnation. Though the Neoplatonists also speak of the divine logos and of its metaphysical presence in the world, they reject the teaching of the Word become human at a particular time in history. For Augustine as for the Platonists, philosophy can provide secure knowledge, because its proper objects are immutable, eternal principles. Historical facts, however—and the incarnation of the logos is such a fact—are bound to space and time. They come into being and pass away. They cannot be grasped by intellectual evidence but have to be believed, mostly by crediting testimonies made by others: eyewitnesses, the Gospel writers, or Church tradition.
Thus Augustine claims that the incarnate son of God is not accessible by philosophy but only by faith. Since recognition of the incarnation is the way for us to become humble and open ourselves for God’s grace, faith is required for the healing of the soul. All attempts to become virtuous through one’s own efforts must in principle remain fruitless, and even worse, they give testimony of human pride and haughtiness. To admit one’s inability, to shed tears of confession, this means to take the humility of the divine logos as a model and to become meek oneself. If we humbly admit our inability to attain the good, then, Augustine asserts, God in his grace will bestow on us the strength to change our lives and to live according to our insight. For Augustine, the strength of philosophy, namely its power to provide insight, represents also its weakness, because intellectual evidence is unable to approach and appropriate Christ’s work of salvation.
Augustine characterizes the wisdom of philosophy as a proud wisdom as long as it does not acknowledge the limits of its competence. In its best form, it is a valid theory—even and especially in the sense of the Greek theoria, noetic vision—but it must accept that such theory is solely a matter of knowledge that has to be supplemented by a reformation of the will, a therapy, a conversion. Augustine clearly grants philosophy its epistemological claims to a large extent, but he disputes its capacity to transform the human will from evil to good. Philosophy may be the love of wisdom, but this love remains unhappy, according to Augustine, if it does not recognize that it is unable to attain the object of its striving without faith. With his critique of the project of philosophical wisdom, Augustine simultaneously restricts the power of knowledge in order to make room for faith.
Whereas for Plato and Plotinus the ascent to knowledge is necessarily accompanied by moral reform, Augustine separates the aspect of ethical refinement from the aspect of noetic vision and thereby reduces the Platonic endeavor to a mere acquisition of knowledge. He accounts for this separation through penetrating anthropological observations, which he develops once again by critical interaction with ancient philosophy. These observations, which in turn have exercised enormous influence on the modern notions of the human, cannot be outlined in detail here, but they deserve brief mentioning.
First, Augustine makes the will independent from reason. One cannot call this voluntarism in the fullest sense, but it is a clear rejection of so-called “Socratic intellectualism.” Albrecht Dihle regards Augustine as the “inventor of our modern notion of the will” precisely for this reason. Augustine, he argues, emphasized that the will does not by implication follow the judgment of reason but is autonomous over against it.26 According to the famous thesis in Plato’s Protagoras, moral wrongdoing is rooted in a deficiency of insight into the true standing of a good or an ill caused, for example, by passions that cloud the intellectual gaze or, to some extent, by perspectival illusion: goods that are temporally near appear greater than temporally remote ones even if, seen objectively, they are lesser.27 For Plato, philosophy is an art of measurement—that is, the skill that overcomes perspectivity and recognizes the objective magnitude of goods and ills.
In contrast, Augustine explains in his Confessions that he acquired all the knowledge of God that the highest and best philosophy had to offer. Guided by the writings of the Neoplatonists, he claims even to have attained the noetic vision of God but still could not stop striving for finite goods like honor or sexual lust as ultimate goals. “All doubt had been taken from me that there is an indestructible substance from which comes all substance. My desire was not to be more certain of you but to be more stable in you.”28 Insight does not entail a new orientation of one’s way of life because the latter requires an act of the will, which must be performed independently and which can at times fiercely resist better understanding. This is the reason why humans, in Augustine’s image, have not only to scale a mountain but also to cross a sea. If the will is independent from the understanding, the achievement of perfect understanding does not suffice to set right the will.
Second, in addition to the independence of the will over against the intellect, Augustine introduces another novelty—the notion of a division of the will. He deems it possible that even if the good burgeons in the will and the human wants to turn towards the good, he is nonetheless incapable of doing so. In this case, the will finds itself in contention with itself. Augustine thus develops a true conception of a weak will, which—unlike in Plato’s Protagoras (or even in Aristotle’s works)—is not based on a mere deficiency of knowledge. In Confessions VIII Augustine describes how he suffers from a divided will. One of its components follows the insight gained by reading the Platonists and strives for the true good, but another component remains imprisoned by old habits. He already has a new good will, but simultaneously he still has his old perverted will so that the new will cannot assert itself.29 The will is thoroughly split, so that its division cannot be healed through the will itself. Augustine describes the dichotomy of the will with words from Paul’s letter to the Galatians, “For what the flesh desires is opposed to the spirit, and what the spirit desires is opposed to the flesh” (Galatians 5:17) and from the letter to the Romans, “I do not understand my own actions. For I do not do what I want, but I do the very thing I hate” (Romans 7:15). This is Augustine’s situation after studying philosophy. Thus Augustine maintains that philosophical insight is incapable of resolving this dilemma of the will. Reason alone cannot make us virtuous. The self-blockade of the divided will cannot be dissolved through understanding, not even through a strenuous act of the will itself. It can only be resolved by God’s help, which requires from a person an acknowledgement of weakness and consequently an attitude of humility.30 Philosophy is incapable of liberating humans from their self-dividedness. Therefore, the ship that can carry across the sea must be carved from the wood of the cross.
Thirdly, Augustine criticizes the Hellenistic ideal of eudaimonia as unrealistic, at least as concerns earthly existence. A felicitous life is utterly unattainable here on earth, which, at best, can be a life lived in the hope of happiness.31 There are two reasons for Augustine’s comparatively pessimistic estimation of what may be expected from earthly life. First of all, happiness, according to him, necessitates eternal life. Happiness thus—in contrast to what Epicurus and the Stoics believed—cannot occur in mortal existence. Happiness remains reserved for a transcendental existence. Second, Augustine regards the Platonic ideal of the virtues as exaggerated. In Plato’s Republic, justice includes not only wisdom and courage but also prudence, according to which the lower parts of the soul understand that they should allow themselves to be guided by reason and do so gladly. The just therefore live in harmony, tranquility and inner peace.32 For Augustine, on the contrary, virtue is an instrument in the inner struggle. Even the converted person, he contends, is constantly in danger of falling into the ways of this world and has to perpetually collect himself and direct himself anew towards God. The passions consistently strive for dominion over reason, and false self-love seeks the subtlest ways of gaining advantage. Although the will of the converted person is firmly aimed at God, the passions still have to be actively restrained. Humans remain subject to temptation, Augustine claims. Constant self-examination is thus required in order to assess whether one’s way of life is really determined by a good will or whether a false self-love has subtly intervened.33 Due to a constitutional diremption, humans can never attain in earthly life that psychical uniformity and inner peace Plato attributes to the just. Therefore, in Augustine’s view, the Greek ideal of eudaimonia is unrealizable in earthly life. Philosophy, he concludes, cannot lead humans to self-unity, and even faith, in this respect, can ultimately only awaken the hope of transcendental perfection.
At a few but significant places, Augustine speaks of Christian faith as philosophy. In De vera religione (8, 25) Augustine says, “We Christians hold the view . . . that philosophy, that is striving for wisdom, is not different from religion.” And in Contra Julianum (IV 72), he urges Julian: “Do not estimate pagan philosophy higher than our Christian philosophy, which is the one true philosophy, because the word ‘philosophy’ signifies the search and love of wisdom.”34 If Augustine distinguishes reason and faith in the manner described above, how can he speak of Christianity as “true philosophy”?
What Augustine has in mind at these places is the claim of ancient philosophy to convert humans and to provide wisdom so they can attain ultimate happiness. As manifold and heterogeneous as the different schools were, Hellenistic philosophy contains a common focus in the idea of an ars vivendi—the art of life—which enables humans to lead a good and successful life.35 This good life allows human nature to evolve and attain perfection against all cultural deflections. The human who lives well knows which of the many offered goods is the highest and how one reaches it. Indeed, humans strive for the happiness that results from the possession of the summum bonum in everything they do, but due to the influence of errors and false dispositions, they mostly search for the highest good in the wrong places. According to the common conviction of the major Hellenistic schools, the task of philosophy consists, first of all, in the elaboration of an adequate conception of the highest good in order to dispel human ignorance of the truly good, and, second, in the development of inner attitudes (namely virtues), which give humans a set orientation in their ways of living so that they may attain the highest good, possess it and out of this possession enduringly act justly. “Wisdom” designates the condition of perfection in which humans have appropriated the summum bonum and henceforth lead a good and happy life. The purpose and goal of philosophy, therefore, is to free humans from their ignorance and vice and help them become wise.36
The Platonic-Neoplatonist philosophy—which, for Augustine, represents the best philosophy in general—operates with the notion of human perfection, too. The ascent out of the cave in Plato’s parable leads humans to the pinnacle of their possibilities of being, both in terms of their understanding and with respect to virtues.37 For the goal of the movement is the intellectual vision of the idea of the good. This ascent is a cognitive-voluntative double endeavor, just as the elevation to the vision of the divine in Plotinus’s Enneads I 6, “On the Beautiful,” presupposes and brings about a moral purification of the soul.38 The perfection of human life cannot be procured by way of a one semester course in Plato’s doctrine of ideas. It obtains rather at the end of a decade-long cultivation process that entails both an expansion of a person’s understanding and a re-formation of her orientation of values.39 From a Platonic perspective, philosophy constitutes the decisive means on the path to human perfection. It is the philosopher who descends into the cave, loosens the chains of the cave inhabitants, compels them to conversion and accompanies them to the exit. Along this path, those released themselves become philosophers, i.e., virtuous humans capable of intellectually gazing directly into the sun.40
Augustine, however, levels a penetrating critique against Neoplatonist philosophy in particular and against the ancient philosophical project of ars vivendi in general—a critique that concerns the scope, the power, and the claim of philosophy. Philosophy, according to Augustine, is valuable because it can help people come to the path of wisdom and advance along it. He contends that it cannot, however, lead humans to the goal of that path. This step is reserved for religious faith. What is more: he states that philosophy is not only insufficient for attaining the goal of life; it is not even necessary for it because religious faith can equally fulfill the signposting function of philosophy. While Augustine concedes that it is better if philosophy assumes this task, he insists that if this is not possible—for example, because someone does not possess the required education or is occupied with a common profession such that he does not have the requisite leisure—faith suffices. In Augustine’s view, ancient philosophy made a pledge which it was never able to redeem. For him, only Christianity can fulfil the promise of wisdom originally made by philosophy. In this sense, he calls Christianity “true philosophy.”
Although Augustine holds philosophy to be neither sufficient nor necessary for salvation, he engages quite a lot in this business. In fact, a large part of the Western philosophical heritage can easily be traced back to Augustine. Why does Augustine do so much philosophy? Philosophy allows him to give a clearer exposition of Christian faith. I will mention just three examples of the use Augustine makes of philosophy. First, in De libero arbitrio II Augustine develops a philosophical proof of God’s existence. Second, in De civitate dei XIX Augustine takes up a philosophical discussion with the Epicureans, the Stoics and the Peripatetics to show that their notions of human fulfilment are inaccurate. Augustine adduces philosophical anthropology to claim that humans by their very nature long for eternal life, not for pleasure alone, or virtue alone, or even both combined. Then he tries to show that Christian faith is the only means to obtain what everybody wants. Anthropology does not give proof of Christian faith. The idea that God became human could still be false. However, Augustine’s philosophical argument is meant to expound the relevance of the Gospel by showing that humans have a natural desire (a desiderium naturale as Aquinas puts it), a desire which—in Augustine’s terms—makes our hearts restless until they rest in God, as promised by faith. Augustine demonstrates not the truth, but the relevance, of faith by philosophical anthropology.
The third example is De Trinitate, Augustine’s speculative masterpiece. Augustine sets out to explain what Scripture means when it calls humans images of God. First he develops a theological notion of the divine trinity. Then he gives a philosophical analysis of the human mind. If humans are created in the image of God, the decisive feature must be detectable by a philosophical analysis of human nature. Augustine finds a Trinitarian structure in the human mind, corresponding to the structure of divine trinity. The theological part of the argument enables Augustine to reserve the mystery of divine trinity for faith. The philosophical part, however, allows him to explain to believers and non-believers alike what faith refers to when it states that humans are likenesses of God. In De libero arbitrio II as well as in De civitate dei XIX and in De Trinitate, Augustine uses philosophy to give support and a clearer exposition to faith.
Since Augustine was considered an uncontestable authority in the Middle Ages, it is not surprising that one frequently encounters his estimation of philosophy and its relationship to religion during this time. At the very beginning of his Summa Theologiae, Aquinas discusses the relationship of philosophy and theology. “Do we need another doctrine beside philosophy?” is the opening question of the entire work. Aquinas’ answer is well known. Yes, we do need another doctrine, the so-called sacra doctrina or theologia, without which humans cannot reach their final destination, namely happiness in the vision of God.41 Augustine criticizes philosophy not by contaminating reason with faith, but by restricting the range of reason to theoretical insight that cannot change our lives. Imposing limits on knowledge and thus making room for faith is truly Augustine’s achievement. When Aquinas declares philosophy insufficient, he draws on Augustine’s critique of ancient thinking. The bishop of Hippo paved the way for Aquinas’ claim that we need another doctrine beside philosophy, namely the sacra doctrina that is based on faith.
Obviously, Aquinas’ answer rests on a separation of philosophy and theology, for if the two were identical, his thesis about the necessity of theology in addition to philosophy would be nonsensical. Like Aristotle, Aquinas holds a deductive concept of science. To do science means to derive judgments from given principles. According to this view, sciences are identical if they rest upon the same principles; otherwise they are different. For Aquinas, philosophy and sacra doctrina do not share the same premises, for the principles of philosophy are self-evident to reason and thus do not require any further grounding, whereas the principles of theology are far from self-evident—or, as Aquinas puts it, they are self-evident only to God and his saints, but not to human understanding.42 Sacra doctrina starts with truths that are obvious for God, but for us need to be accepted in the mode of belief. Whereas philosophy rests upon reason, theology is based on faith. Thus, for Aquinas, theology is different from philosophy.
Given the differences of the two disciplines, what role can philosophy play for the sacra doctrina? For Aquinas, it is the role of a handmaiden.43 The metaphor of the handmaiden is spelled out in three theses. First, philosophy is insufficient for attaining salvation. Even the perfect philosopher needs something beyond philosophy, namely divine grace and faith, to reach the goal of life. Second, philosophy is not even necessary. According to Aquinas, a Christian believer can obtain happiness without doing any philosophy. Philosophy is accessible only for the learned, i.e., for an intellectual elite that has the leisure to occupy itself with abstract theories, while salvation in the Christian sense should be attainable for everybody. Furthermore, human reason is always prone to error, while faith, for Aquinas, is secure. Also, philosophy, even if it deals with God, does not know him as well as faith does, for at its best philosophy might have a correct metaphysical notion of God, but still falls short of what faith knows about God’s actions in history, above all in the incarnation.
Third, despite these shortcomings, Aquinas does not entirely reject philosophy, for sacra doctrina, even though it does not depend on philosophy, can still make use of it. For Aquinas, philosophy is capable of giving Christian faith a clearer exposition (maior manifestatio).44 For example, sacra doctrina uses the metaphysical proofs of God to fend off those who reject Christianity on the ground that no God exists. Also, it uses philosophical anthropology to justify the universality of its claims. If we can show that humans as such long for ultimate happiness, we can argue that all humans should at least listen to the Christian message, because what is promised here is precisely the fulfilment of a universal and natural human desire. Thus, this message must be made known to everybody, and nobody should remain indifferent. Clearly, even for Aquinas philosophical anthropology cannot prove the truth of Christianity, but it can do enough to show that faith makes sense to everybody.
Aquinas’ view of the relationship of philosophy and theology is largely equivalent to Augustine’s. According to both, philosophy is neither sufficient nor necessary for humans to reach their ultimate goal. Instead faith, whose claims exceed the realm of truths accessible to reason alone, plays the decisive role. However, faith is not restricted to super-rational truths, but extends into the realm of reason as well, thereby creating a sphere of overlap where truths of faith and truths of reason coincide. Here sacra doctrina can make use of philosophy and its rational method to explain and defend its own assertions. In numerous passages Aquinas even expressly adduces the authority of Augustine to support his own view of sacra doctrina. For Aquinas the idea that faith beyond reason is necessary goes back to Augustine,45 as well as the view of faith as a source of truths about God, which do not contradict the truths of reason, but either coincide with them or transcend them.46 Thus for Aquinas the scientia fidei is entitled to utilize the arguments of the philosophers, much as the Israelites, according to Exodus 3:22, were allowed to seize the gold and silver of the Egyptians, as Augustine had already pointed out.47
Like Augustine, Thomas Aquinas is of the opinion that philosophy is neither sufficient for the attainment of salvation, because it cannot mediate the grace of God, nor necessary, because everything that is essential to know can be found in Holy Scripture. Nevertheless, philosophy is highly valuable because it is capable of mediating much of what Holy Scripture teaches by authority through the discernment of reason.48
Augustine had considerable influence in modernity. René Descartes, for instance—as recent research has shown—is dependent on Augustine for several central points of his thinking.49 The cogito ergo sum of the second meditation is anticipated in Augustine’s si fallor, sum;50 the proof of God from the idea of infinity in the third meditation recalls Augustine’s proof in De libero arbitrio;51 and Descartes’ arguments for the difference of the mind from the body reflect Augustine’s deliberations in De trinitate down to the very wording.52 Descartes even follows Augustine’s guidelines concerning the question about the possibilities and limits of philosophy. In a letter to Mersenne in March 1642, he distances himself from Pelagius, who made the claim, “that one can do good works and merit eternal life without grace, which was condemned by the Church; and I say that one can know by natural reason that God exists, but I do not thereby say that this natural knowledge, of itself and without grace, merits the supernatural glory we await in heaven.” And Descartes continues, “However, one must note that what is known by natural reason, such as his being absolutely good, almighty, wholly truthful, and so on . . . cannot suffice to attain heaven, because for this one must believe in Jesus Christ and other things that are revealed, which is something that depends on grace.”53 To attain metaphysical knowledge of God is consequently a genuine task of natural reason and philosophy. But the capacity of doing good works by which one achieves happiness is not mediated by philosophy alone. In Descartes’ view, philosophy may prepare humans for moral improvement, but to achieve it does not lie in its power. Since there is no happiness for humans without moral perfection, however, philosophy cannot make people happy. Therapy, in the sense of a moral conversion of the person from evil to good, is therefore not a possible task for philosophy according to Descartes.
The wake of this estimation of philosophy and its limits even reaches Immanuel Kant. His Critique of Practical Reason offers a fundamental determination of moral good and also a theory of the highest good (summum bonum) in which moral good coheres with happiness such that the moral good, although it is a goal in itself, also represents a prerequisite for happiness. Since it is not in our power to bring about this happiness, however, Kant feels justified in postulating the existence of God as a moral ruler of the world who alone can add happiness to virtue.54 Kant criticized the eudaimonism of antiquity—particularly its representatives in Epicurus and the Stoa, which were entangled in the antinomies of practical reason—because it was conceived without recourse to God and thus led to the strange thesis that the appetite or virtue alone is already the highest good.55 A comparison of Kant’s dialectic of practical reason with Augustine’s critique of the Epicurean and Stoic definitions of the highest good would immediately bring many parallels to light.56
I would like to demonstrate Kant’s connection to Augustine on another, deeper point of his ethics. Kant’s ethical theory tells us how humans should be in order to be allowed to hope for happiness—they have to have a good will. But the question of how to acquire a good will is not thereby answered. If we are radically evil, as Kant claims at the beginning of his book on religion, how can we become good?57 This question raises the issue of therapy and with it, as Kant is of course aware, the topic of grace. It is, naturally, a difficult topic because it gives occasion to all sorts of “ignoble religious ideas” and is especially suited to abetting “religions which are endeavors to win favor” in complete contradistinction to “religions of good life-conduct.”58 Nonetheless, philosophy needs to consider the concept of grace. It cannot do without it, for it belongs, as Kant states, to the “parerga [by-works] to religion within the limits of pure reason; they do not belong within it but border upon it.”59 In this context, Kant writes: “How it is possible for a naturally evil man to make himself a good man wholly surpasses our comprehension; for how can a bad tree bring forth good fruit? But since, by our previous acknowledgment, an originally good tree (good in predisposition) did bring forth evil fruit, and since the lapse from good into evil (when one remembers that this originates in freedom) is no more comprehensible than the re-ascent from evil to good, the possibility of this last cannot be impugned. For despite the fall, the injunction that we ought to become better men resounds unabatedly in our souls; hence this must be within our power, even though what we are able to do is in itself inadequate and though we thereby only render ourselves susceptible of higher, and for us inscrutable, assistance.”60
Kant’s move from “ought” to “can” initially sounds quite Pelagian: “we ought to become better men . . . hence this must be within our power.” His further line of thought, however, demonstrates that Kant is ready to concede that Augustine was right when he maintained that human reason could not conduct therapy on itself. For, according to Kant, it is not only the dispensing of happiness to the virtuous but also the prior moral conversion from a radically evil will to a radically good will that is impossible without divine assistance. Humans, he argues, must be allowed to hope that what is not within their power—to become better persons—will be accomplished by higher assistance.61 Philosophy cannot make positive use of the idea of such assistance because it remains incomprehensible to it how my own moral goodness does not emerge from my own act but rather from another being. Grace is not a genuinely philosophical concept. But philosophy need not reject the possibility and reality of a moral-transcendent idea like that of divine assistance for the conversion of character.62 In his own, sober and careful manner, Kant expresses the reservation towards philosophy that Augustine had already formulated. Philosophy knows how humans should be in order to attain happiness, but it might not be able to make them what they should be because self-conversion might be outside the realm of natural human faculties. Therefore, even Kant fosters basically the same reservations toward the therapeutic competence of philosophy as Augustine.
1. E. Gilson, Introduction à l’étude de Saint Augustin (Paris: Vrin, 1969), 311.
2. R. Williams, “Sapientia and the Trinity: Reflections on De Trinitate,” in Collectanea Augustiniana. Mélange T.J. van Bavel, ed. B. Bruning, M. Lamberigts, and J. van Houtem (Louvain: Leuven University Press, 1990), 317–32. Here, p. 323.
3. A full interpretation of Augustine following Williams’ lines is given by M. Hanby, Augustine and Modernity (London: Routlege, 2003). Cf. the review by J. Brachtendorf, “Orthodoxy without Augustine: A Response to Michael Hanby’s Augustine and Modernity,” in Ars Disputandi 6 (2006).
4. See De civitate dei VIII 4; 6-9. For Augustine, there are in fact truths about the eternal that in principle cannot be grasped without God’s revelation, but they are few. These concern primarily (1) the resurrection of the body, and thus the immortality not just of the soul—which can be proved philosophically—but of the entire human being; and (2) the three-foldness of God, not in the sense of a three-principle-teaching, which was already held in Neoplatonism, but in the sense of the Nicene teaching of the sameness of being of the persons.
5. De civitate dei VIII 4.
6. De civitate dei VIII 5.
7. Cf. De ordine II 9, 26. With slight variation, the translation is from The Essential Augustine, ed. Vernon J. Bourke (Indianapolis: Hacket, 1974), 26.
8. De ordine II 13, 38.
9. De ordine II 9, 26.
10. The New Oxford Annotated Bible, ed. B. Metzger and R. Murphy (New York: Oxford University Press, 1991). All citations from the Bible are from this edition. For an example of Augustine’s use of these passages, see De libero arbitrio II 6, 18.
11. See, for instance, De libero arbitrio I 7, 18; 10, 26; II 1, 1–2, 4.
12. Only in his short skeptical phase does Augustine seem to have doubted the feasibility of the promise, “Search, and you will find.” Perhaps this is the reason why he spent so much energy in his early dialogues critiquing skepticism and making it seem ridiculous.
13. Cf. Conf. VII 10, 16–17, 23.
14. Conf. VII 21, 27.
15. Conf. VII 20, 26.
16. Conf. VII 27, for instance, is also instructive. For the following explications, cf. J. Brachtendorf, “Augustinus und der philosophische Weisheitsbegriff,” in T. Fuhrer ed., Die christlich-philosophischen Diskurse der Spätantike: Texte, Personen, Institutionen (Stuttgart: Franz Steiner Verlag, 2008), pp. 261–74 and Augustins Confessiones (Darmstadt: Uissenschaftliche Buchgesellschaft, 2005), pp. 119-88.
17. Cf. In Johannis evangelium tractatus, tr. II.
18. For the distinction between seeing and holding fast, cf. also De libero arbitrio II 36, 141; 41, 161.
19. In Johannis evangelium tractatus, tr. II 3.
20. Ibid., tr. II 3.
21. Conf. VII 9, 13.
22. Conf. IX 4, 7.
23. Retr. I 3, 2.
24. Ibid., tr. II 2.
25. Ibid., tr. II 4.
26. A. Dihle, The Theory of Will in Classical Antiquity (Berkeley: University of California Press, 1982), 144.
27. Plato, Protagoras 352a–357e.
28. Conf. VIII 1, 1.
29. Ibid., VIII 21f.
30. Ibid., VIII 27.
31. Cf. De civitate Dei XIX.
32. Republic IV 434d–445e.
33. The tenth book of the Confessions offers the first literary testimony of such self-examination.
34. Cf. also De civitate dei X 32.
35. On the ethics of happiness, see J. Annas, The Morality of Happiness (New York: 1993). Excellent summaries and discussions of the teachings of the Hellenistic schools can be found in Cicero’s dialogues, especially in De finibus bonorum et malorum, Tusculanae disputationes and De natura deorum.
36. See, for example, Seneca, Epistulae morales 89, 2.
37. Republic VII 514a–518b.
38. Enneads I 6, 9.
39. Plato believes that this is first possible after the age of 50 (cf. Republic VII 540a).
40. Several of Plato’s comments imply that he understands philosophy as the way to wisdom, not as wisdom itself. Cf. Phaedrus 278d; Symposium 204a.
41. Cf. ST I q 1, a 1; Sent I prol. q 1, a 1.
42. Cf. ST I q 1, a 2; Sent I prol. q 1, a 3.
43. Cf. ST I q 1, a 5; ScG II 4; Sent I prol. q 1, a 1.
44. Cf. ST I q 1, a 5.
45. Cf. De veritate q 14, a 9 and 10, with reference to Augustine’s Epistula 147 and De praedestinatione sanctorum.
46. Cf. ScG I 3 with indirect reference to Augustine’s anti-Manichean works; I 7 with reference to Augustine’s De genesi ad litteram II.
47. Cf. In Boetii de Trinitate, proemium q II, a 3, with reference to Augustine, De doctrina christiana II 40, 60f.
48. Aquinas, ST I q. 1.
49. Cf. S. Menn, Descartes and Augustine (Cambridge: Cambridge University Press, 1998); G. Matthews, Thought’s Ego in Augustine and Descartes (Ithaca: Cornell University Press, 1992).
50. Cf. Descartes, II. Meditation, nr. 23; Augustine, De civitate Dei XI 26.
51. Cf. Descartes, III. Meditation; Augustine, De libero arbitrio II, esp. 12, 134–36.
52. Cf. Descartes, II. Meditation, nr. 10; Augustine, De Trinitate X 15f.
53. Oeuvres de Descartes, ed. C. Adam and P. Tannery (Paris: Vrin 1969–1976), vol. III, p. 544.
54. Cf. Kant, Critique of Practical Reason, A 220–38.
55. Ibid., A 198–216.
56. Cf. De civitate Dei XIX.
57. Kant, Religion within the Limits of Reason Alone, Book One (“On the radical evil in human nature”).
58. Ibid., B 62.
59. Ibid., B 63n.
60. Ibid., B 50.
61. Ibid., B 62.
62. Ibid.