Thomas Aquinas is celebrated for many things in the history of Christian theology, but one is the revolutionary place he gives to the thesis that the incarnate Christ acquired knowledge by way of empirical experience.Footnote 1 That his claim should be so revolutionary surely strikes us today as very odd. Any reflection on Christ's knowledge ordinarily seems to begin today by stressing how, in becoming one of us, the Word of God assumed our ordinary human limited ways of knowing.Footnote 2 Only then does the theologian of the incarnation seem to move on to think about what might be extraordinary in the knowledge of Christ's human mind, something that is almost by way of exception to the general rule, and this is often where the difficulties for theologians begin. Did Christ really possess the heavenly knowledge of the beatific vision during his earthly lifetime? Did he in fact possess the knowledge of prophecy or the knowledge appropriate to angels? Such questions raise problems for the contemporary theologian, because such modes of knowledge are often taken to make Christ appear a rather superhuman or mythical figure, at one remove or more from the authenticity of our more limited humanity. Since Karl Rahner famously pointed this out at the beginning of the latter half of the twentieth century,Footnote 3 Catholic theologians have found themselves as a matter of course in a position of taking Christ's ordinary knowing as a given, but more uncomfortable with traditional accounts of his extraordinary knowledge. However, when we turn back to medieval times, we find quite a different situation, where theologians like Albert the Great and Bonaventure were universally comfortable with Christ's extraordinary knowledge, but found it extremely difficult to accept that Christ acquired any knowledge by the normal human, empirical, experiential route.Footnote 4 Here I want to say something of the revolutionary role Aquinas played in helping us admit the reality of Christ's ordinary human knowing, and the role that his philosophical commitments played in his theological advance, within the wider context of the soteriological character of his Christology. However, I also want to draw attention to some of the problems involved in his particular theological position on Christ's acquired knowledge and his wider picture of Christ's knowledge, showing among other things how the very same philosophical means that enabled Aquinas to recognise the reality of Christ's acquiring knowledge also led him into giving an overall picture of Christ's knowledge that was not so satisfactory. At the same time I want to suggest that part of the solution to the difficulties into which Aquinas gets himself is to be found in a philosophical position already employed by him in his mature account of Christ's knowledge.
It is in the Third Part of the Summa Theologiae that Aquinas tackles the question of Christ's acquired knowledge, and stated his well-known position.Footnote 5 He does so in the context of considering Christ's incarnate knowledge in general, treating his extraordinary, supernatural means of knowledge first,Footnote 6 before going on to his natural, acquired knowledge. However, it is worth noting that even before he looks at these different kinds of knowledge that co-exist in Christ's single human mind, he takes himself to be obliged to ask whether Christ had any kind of knowledge at all besides the divine knowledge that pertains to divine nature, to the divine mind.Footnote 7 Here we can sense the two-nature Christology of Chalcedon at work, and we should note that, though Catholic orthodoxy, expressed in such conciliar gatherings as Chalcedon, was the common framework of Aquinas's theologian contemporaries in the West, he was particularly knowledgeable of this tradition because he was the first among them to obtain and get to grips with the texts and immediate background of the councils themselves.Footnote 8 In the Summa's questions on Christ's knowledge then, we can see Aquinas operating within this framework of Chalcedonian orthodoxy – one person in two natures, divine and human – in such a way that he was sensitive to other possible Christological positions and their implications. He knew that the view had been in circulation in various forms that the incarnate Christ had only divine knowledge.Footnote 9 This view had in fact become current in the East among the disciples of Severus of Antioch, who rejected Chalcedon's two natures as conceding too much to the Nestorian duality of divine and human in Christ. While avoiding talk of two natures, these theologians accepted the reality of Christ's human mind but denied that it had any distinct knowledge of its own pertaining to Christ's humanity as such. Instead the divine knowledge of the divine mind did for Christ's human mind, his humanity, as it did for his divinity. The idea that Christ might be said to have only one knowledge, one wisdom, was used to bolster those who wished to give a radical emphasis to Christ's unity, over against the Nestorians and indeed Chalcedon, where Chalcedon was taken to have sold out to Nestorianism with its two natures, and it was allied to the Monothelete position that the incarnate Christ had only one will and activity.Footnote 10 Through his research Aquinas had access to the documents of the Third Council of Constantinople, which condemned Monotheletism. Interestingly, Aquinas says in the Summa that this Council condemned those who denied two wisdoms in Christ.Footnote 11 Not that the conciliar text, which is concerned with the question of how many wills and activities there are in Christ, actually speaks explicitly of one or two wisdoms,Footnote 12 a fact Aquinas doubtless knew. Rather Aquinas is reflecting here his awareness of the background of the Council,Footnote 13 no doubt seeing knowledge as covered by activity, meaning that the idea of one wisdom was just as much excluded by the Council's teaching as was the thesis of one will and activity, a position clearly consonant with Aquinas's own understanding of the close interrelationship of intellect and will.Footnote 14
However, we should also note that the idea of one wisdom, or at least hesitations about affirming a second, human wisdom, had been revived more recently, and in the context of the Chalcedonian Western scholasticism of the twelfth century. This can be found in Hugh of St-Victor, and in the Summa Sententiarum, which says: ‘It is important to state without any hesitation that in Christ there was not any wisdom other than the divine wisdom.’Footnote 15 Peter Lombard's Sentences took a different view, distinguishing a divine wisdom or knowledge and a human wisdom or knowledge, the former pertaining to the divine nature and the latter to the human nature.Footnote 16 Aquinas's thirteenth-century contemporaries commented on the Sentences as a matter of course, and they too took Peter Lombard's view.
In order to grasp how Aquinas argues for his Christological conclusions, we can look more widely in the Summa than his question on Christ's knowledge. The Third Part of the Summa follows his treatment of God in himself, and God as the beginning and end of all things, the source and goal of creatures, especially the human creature who is made in the image of God and returns to God by way of the gracious elevation of this image through grace to glory. The Third Part treats precisely of how this return of the human creature takes place, that is, through the incarnation, where the grace lost by the Fall, that is, the seed of glory, is restored through the salvific taking flesh of Christ, the way to the Father: ‘I am the way,’ as John's Gospel, puts it (14:6). It is Christ as the way that sums up Aquinas's Christology, and this shows itself in how he answers theological questions about Christ in terms of the human need for salvation. It is not so much that Aquinas says that Christ's humanity has to be thus and so just because he is God incarnate: rather his humanity has to be thus and so for the sake of our salvation. Of course Christ's humanity has to be complete for the sake of our salvation: the incarnation requires an intellectual soul as well as the body because that is what is required for the economy of salvation. But so is not only the complete humanity that is assumed: so is what is co-assumed in the incarnation.
Having treated the human nature assumed in the incarnation in the first six questions of the Third Part – Aquinas turns in questions seven to thirteen to what is co-assumed in this assumption of human nature.Footnote 17 Here we have by and large not the essentials of human nature that come with the basic human kit, body and soul, but rather the perfections and defects that might or might not come with human nature as such. As we shall see, Aquinas mainly argues for these co-assumed features not on the basis of some kind of absolute necessity consequent on human nature or divine incarnation, but on the basis of what is necessary on the condition that the incarnation is for the sake of our salvation, which God has wisely decided should take place in a certain way.Footnote 18 Aquinas holds that our salvation did not have to take place in the precise manner in which it did, that is, through the cross and so on, but this is the fitting way God's wisdom has decreed.Footnote 19 Given that the incarnation takes place with this saving end in view, it is our salvation and its mode that determines what should be co-assumed in the incarnation, whichever perfections and whichever defects.
For example, as regards Christ's saving defects, Aquinas includes defects of both body and soul.Footnote 20 As regards the body there are death, hunger, thirst, passibility and so on, and as regards the soul there are pain, sorrow, fear, anger and so on. Aquinas's discussion seems to presuppose that an incarnation of a divine person need not involve such things. In that sense they are not necessary, not absolutely inevitable for an incarnation. God is powerful enough to become a human being, say in a heavenly state where all such things will have passed away but in which its human inhabitants in their glorious condition will be no less completely human for all that. That the Word of God had in fact assumed such things as suffering and sorrow was instead necessary on account of the manner by which we were to be saved.Footnote 21
The same can be said for the co-assumed perfections of Christ's humanity. Among these is the habit of grace in Christ's soul, what Catholic theology normally calls ‘sanctifying grace’, and Aquinas treats of Christ's grace in questions seven and eight. He gives three reasons why sanctifying grace is necessary in Christ's soul.Footnote 22 The first sounds initially as though this grace were of absolute necessity to the incarnation. This reason is the proximity of Christ's soul to the Word in the hypostatic union. From the principle that the nearer anything is to the cause acting upon it, the more it will be affected by that cause, Aquinas concludes that it was maximally fitting that Christ's soul receive an infusion of divine grace. Now this argument makes no reference to the soteriological purpose of Christ's humanity, but rather depends on the fact that this humanity is God's. It would seem to count for any divine incarnation, whatever its purpose might be. However, we should note the fact that Aquinas concludes only that the proximity of divinity makes it only very fitting, not absolutely necessary, that the soul of the Word incarnate be blessed with the habit of grace. In other words, Aquinas can envisage the theoretical possibility of an incarnation of a divine person taking place without that habit. What clinches the necessity of this grace in Christ are two further reasons, each one more explicitly soteriological, namely, that this grace support acts of Christ's knowledge and love that our Saviour in the dignity of his office must make to fulfil the plan of salvation, and that as Head of the human race Christ should have grace to pass it on to those whom he saves, the members of the Body sharing in the grace of the Head. Perhaps there is in Aquinas's mind a definite leaning towards the perfection of grace in Christ's soul prior to his deployment of more soteriological reasons – perfection as a kind of default position – but the soteriological reasons are required to clinch its necessity. Where Aquinas can see a soteriological reason for a defect rather than a perfection, he accepts it, but in this case a lack of grace is a non-starter for our salvation, while the presence of grace is nothing of the kind.
We have something similar in the case of knowledge or scientia in Christ's human soul, to which Aquinas turns in question nine: the perfection of knowledge in Christ is conducive to our salvation, while its absence would not be. In one way, though, his co-assumption of knowledge, in the broader sense of the word scientia, seems to be of absolute necessity, given that it is essential to human nature. This is the natural grasp of first principles that, on Aquinas's account, just comes with the intellectual soul.Footnote 23 It would seem that Aquinas cannot envisage an incarnation of a complete human nature without it. When treating of scientia in the strict sense of the word, Aquinas has two more arguments.Footnote 24 One is an appeal to the Aristotelian principle that everything exists on account of its activity. However, if Christ did not operate through his intellectual soul, that is, have created knowledge, his created mind would have existed in vain. Given that it existed for the sake of its activity and not in vain, the soul had its own created knowledge. Of course Aquinas would have accepted that as a matter of fact many instances of a species might fail in coming to perfection by its proper activity. In this case, however, he is assuming that Christ will not fail, and here we can spot his soteriological concern that manifests itself most clearly in Aquinas's most important argument for Christ's human knowledge, the one he places first in order. Here he appeals to the principle of the divine saving plan that the human race was to be brought to perfection through Christ's human nature. This meant that Christ's human nature had to be perfect, perfected through its own proper knowledge. Without this knowledge, the human mind would have remained in potency to an unrealised knowledge, and to that extent would have been imperfect, remaining ever a tabula rasa, and unsuited for bringing us to perfection.
Having established that there is human knowledge in Christ and not just divine knowledge, Aquinas goes on to determine in what that knowledge consists, and he argues first for a beatific knowledge, that sharing in the divine knowledge enjoyed by the angels and saints in heaven, secondly for an infused knowledge equivalent to that which is natural to angels, and thirdly for the acquired knowledge natural to human beings. In each case his argument for Christ's possession of this particular kind of knowledge is more or less soteriological in character. For example, he says that Christ has the beatific vision for the purpose that he can bring us to share this vision, not that it followed on from the grace of union by some kind of unavoidable metaphysical necessity.Footnote 25 Then for Christ's infused knowledge he argues from the perfection due to Christ which, as we have seen, is crucially due to him as our Saviour who leads us to perfection.Footnote 26 As for Christ's acquired or experiential knowledge, Aquinas recalls the fact that there is nothing lacking to Christ's human nature (which is of course for our salvation), and the Aristotelian principle that ‘God and nature do nothing in vain’.Footnote 27 With regard to the latter he adds that much less can there be something vain in the soul of Christ. The implication is that, though individuals may of course fail in certain cases, in Christ, who is our Saviour, there is no such failure, and his own human intellect will have the proper activity for which the human intellect itself exists.
I want to draw attention to the fact that, in the context of the overall soteriological thrust of Aquinas's Christology, the crucial move here is philosophical. It is Aquinas's Aristotelian account of human knowing that makes all the difference, and in particular his deployment of the distinction between the active intellect and the passive intellect he takes from AristotleFootnote 28 and the nature of which he disputed with other interpreters of Aristotle and his contemporaries.Footnote 29 Not that Aquinas holds in this that there are two quite separate intellects, one active and one passive, but that the single intellect is twofold in this respect, active and passive. It is the role of the intellect as active to abstract from sense images and material conditions what Aquinas calls the species intelligibilis. It is this immaterial species that is then received into the intellect as passive as the basis of the act of knowledge, as that by which a human being makes an act of knowledge. The species brings the same form of what is known in the world, what exists there materially in individuals, to exist in the mind in an immaterial way, a kind of union between mind and world where the mind is conformed by this form to what is known. These species, abstracted from the individual and material conditions of the realities known, provide a universal and general knowledge of the natures known. They answer to the kind of ‘scientific’ knowledge for which the immaterial human intellect, on Aquinas's account, is in potency, and which it desires for its perfection.
It is because Aquinas thinks of the intellect in this active as well as passive sense that he deduces that, without the active intellect's proper operation of abstracting intelligible species from sense data, it will have existed in vain. Since this is not fitting for the kind of Saviour in which Aquinas believes, he concludes, contrary to the general opinion of his time, that Christ must have acquired knowledge. Aquinas admits here that he has changed his mind from his earlier opinion, which he expressed in his commentary on Peter Lombard's Sentences.Footnote 30 What I want to note is how Aquinas managed to change his teaching, that is, he did so on the basis of his philosophical distinction between the passive and the active intellect, rather than because of how he read particular texts of Scripture. One might think he was decisively influenced by Lk 2:52: ‘Jesus increased in wisdom,’ concluding that such an advance must imply the acquisition of knowledge, and he certainly knew that Ambrose had at least sometimes taken Luke in this way.Footnote 31 The Fathers, however, had often interpreted this advance as an advance in the manifestation of Christ's wisdom, or as an advance in those who observed Christ's wisdom more clearly or became gradually more wise through it.Footnote 32 Another possibility might have been of course that his wisdom increased by extraordinary rather than ordinary means. In his earlier position Aquinas had in fact thought of Christ's ‘progress’ in terms of an extraordinary knowledge he already possessed but never increased being progressively related to new sense data.Footnote 33 Thus Aquinas was not even confident enough to present Lk 2:52 in the Summa as biblical evidence for Christ's acquired knowledge. Only once he has established the fact of Christ's acquired knowledge does he employ Lk 2:52 to argue for its progress. Likewise he does not argue from the fact that Christ asked questions to the fact that he acquired knowledge through the answers he received. Aquinas was familiar enough with the exegetical tradition stemming from Origen that Christ already knew the answers to his questions,Footnote 34 and it is true enough that teachers often do use the educational technique of asking questions to which they already know the answers. Aquinas does, however, use Heb. 5:8 as evidence for Christ's acquired knowledge.Footnote 35 This is not without problems, though, and I shall return to this verse later on. For now I want to restate that it does not seem to be anything particular in Scripture that changes Aquinas's mind, but rather the philosophical distinction between active and passive intellect, set in the context of Aquinas's soteriological theological programme, which is of course based on a broader reading of the Scriptural narrative.
I want to turn now to some of the difficulties that more recent theologians find with Aquinas's account. The first is that in acquiring knowledge, the Saviour never learned from anyone else: as the Teacher of all, it was not fitting to his dignity that anyone else teach him.Footnote 36 This runs counter to what we often assume the incarnation involves: Mary and Joseph and others teaching Jesus the basics of human living and so on, and Jesus learning humanly from them in the normal human way. One observation we should make here is that Aquinas held that it was more noble for anyone to acquire knowledge for himself through discovery than to be taught by another; better to find out for oneself than be told by someone else.Footnote 37 Christ the Teacher of all would in his perfection be the ultimate example of this, always discovering for himself and not learning from any teacher, acquiring knowledge through observation of the world around him and reasoning, rather than acquiring knowledge as a learner from a teacher, gaining knowledge from the world, the words God had given, rather than through the words uttered by a human teacher. Now this might sound terribly implausible to us if we suppose Aquinas to mean here that Christ never found out or in his perfection could never find out anything from anybody else, as though he could never have found out the location of some place such as the Sea of Galilee by hearing it from somebody else who already knew. But what Aquinas is always explicitly speaking about in this question is the perfection of scientia – scientific knowledge – rather than any more general receiving of knowledge, factual information, from others. For the Aristotelian Aquinas, ‘science’ for the human mind as such is a general, universal kind of ordered knowledge, a knowledge by way of causes, and it is this that fulfils the potency of the human intellect, and this that Christ acquires for himself and not through teachers. So I do not think we need to suppose that this means that Christ never found out anything from his parents or anyone else, only that he always obtained a scientific knowledge of what he was presented with ahead of any attempts by others to convey any knowledge to him at this scientific level. He was always one step ahead of his ‘teachers’. Does this detract from the reality of his humanity and turn him into a myth? I do not see that being a step ahead of one's teachers makes us any less human. But, more recent theologians ask, need it detract from Christ's dignity as our saving Teacher that he sometimes allow himself to be taught scientific knowledge by someone who already knows? After all it would not seem to be a part of Christ's saving mission to convey to us scientific knowledge in general, but rather something of his unique knowledge of the Father.
More recent theologians also find problems with what Aquinas holds the perfection of Christ's acquired knowledge to involve. Aquinas interprets the perfection of the active intellect to mean that Christ knew by this means everything that can be known in this way, or else his active intellect would have remained in potency to something of which he could acquire knowledge, and would thus have remained imperfect.Footnote 38 In other words, he achieved scientific knowledge of everything of which scientific knowledge can be had by some point in his earthly lifetime, either by direct observation, or by reasoning on the basis of his observations to effects and so on he had not actually observed.Footnote 39 Since it is a general scientia we are talking about, not a knowledge of particulars, a general knowledge of birds, say, rather than the individual details of every particular bird, Christ did not need to experience everything himself, but rather what he knew empirically was enough to allow his mind to form a complete scientific knowledge of birds and so on.
Before moving on to the standard problems had with this position I should say that the way Aquinas's argument develops raises problems for his Scriptural basis for Christ's acquired science. As I have already noted, Aquinas chooses Heb. 5:8 to argue for the fact of Christ's acquired knowledge: ‘Although he was a Son, he learned obedience through what he suffered.’ Aquinas draws on a gloss to interpret this as knowing by experience.Footnote 40 However, it is far from clear that this fresh experience of immense suffering shows Christ acquiring scientia as such. It is not clear to me what new scientific knowledge Christ was acquiring in his passion, especially in view of the fact that Aquinas soon after makes it clear that everything had already been acquired by the time Christ reached the ‘perfect age’ of thirty,Footnote 41 the age he must fittingly reach before he sets about his ministry of teaching.Footnote 42 I suspect that Aquinas was working out his change of position even as he was writing, and that this partly accounts for the presence of remaining difficulties in his account.
The main problem had with Aquinas's account of perfection here is that we find it impossible to suppose that all scientific knowledge could be acquired in so short a space of time, especially given how vast our scientific knowledge now is. Of course Aquinas would have had a different, in retrospect mistaken, sense of how much there is to know, and of how great a proportion of this was already indeed known by such people as Aristotle and his own teacher, Albert the Great. In its historical context Aquinas's claim that Christ acquired knowledge of everything that knowledge can be acquired of does not sound so absurd or mythological. Yet, because of our more advanced position in the history of science, it does appear so, and we cannot suppose that Christ had time or the technology at hand to acquire complete scientific knowledge by human means. Does this mean though that Christ must be stripped of the perfection of his active intellect? Not if we are ready to draw in a different way on what Aquinas's philosophical position has to say about the perfection of the active intellect. Aquinas realises that before Christ acquired all scientia, he would not have possessed all scientia, leaving his intellect for some time in potency and somehow imperfect. This forms the basis of an objection Aquinas puts to the fact of growth in Christ's knowledge: growth implies an earlier state of imperfection, and one cannot ascribe imperfection to the scientia of Christ.Footnote 43 Likewise we could form our own objection to the perfection of Christ's knowledge: given that it does indeed grow, one cannot avoid saying Christ's acquired knowledge was at least at some point imperfect. Aquinas responded philosophically to his own objection by distinguishing two kinds of perfection.Footnote 44 One we might call the absolute perfection of the active intellect, where everything the active intellect could acquire is now acquired; the other we might call a relative perfection, relative to each moment of progress towards this goal. Before attaining absolute perfection, Christ's acquired knowledge was always perfect in this second sense, that is, perfect relative to that particular time and its conditions. From this principle, Aquinas can reply to his own objection that Christ's acquired knowledge always had the appropriate kind of perfection, such that growth was not excluded. And from the same principle we can reply to our own objection, saying that growth does not exclude that perfection which is relative to the moment. Given that we think that Christ could never have plausibly attained absolute perfection of acquired scientific knowledge during the limited period of his earthly lifetime, since unlike Aquinas we know how truly immense science is, we can maintain that this does not detract from the earthly Christ's perfection, since his acquired knowledge was always appropriate to whatever happened to be the moment in time. Aquinas's notion of ‘relative perfection’ is thus plausibly extended from his account of the earthly Christ as a child to explain the perfection of our Saviour's acquired knowledge throughout his earthly lifetime.Footnote 45
One final difficulty is that, on Aquinas's account, Christ already possessed a full scientific knowledge by way of species that were infused into his human mind from the moment of his conception.Footnote 46 One objection that Aquinas puts to Christ's acquisition of species through experience was that Christ already possessed infused knowledge. He answered this by stressing the difference between the species involved in infused and acquired knowledge: the infused species are not abstracted from sense images, coming to the intellect through the imagination, and hence there can be in Christ's soul both species connected to the sense images and species in themselves unconnected.Footnote 47 However, these species, infused from Christ's conception, do give him a scientific knowledge equivalent to and greater in content than that acquired empirically. Not being abstracted from material conditions, Aquinas sees them as containing knowledge of individuals within knowledge of the universals. This is how angels, who do not have bodies and bodily senses, have science, and what Christ is given is a knowledge that is natural to angels. So, by the time he comes to write the Summa, Aquinas sees these species as affording Christ even knowledge of the future.Footnote 48 So in theory Christ could always know what was going to happen, though Aquinas doubtless supposes that he did not always use this knowledge and was normally content to receive information through the senses. Nevertheless, this does appear to undermine the importance of Christ's acquired knowledge, if he already has a complete set of species proportioned to his created mind by which he knows everything he could acquire knowledge of in his earthly lifetime and more. Though it is evident in Scripture that Christ indeed had extraordinary knowledge of some such kind, did he really need it to this maximal extent?
Aquinas thinks Christ needed this full extent of infused knowledge for the perfection he required to be our Saviour. It seems to me that, while his philosophical distinguishing of the active from the passive intellect allowed him to discover how Christ's intellect came to perfection through acquired knowledge, this philosophical distinction more unhappily also allowed him to conclude that this maximal extent of infused knowledge was required for the perfection of the passive intellect from conception, a perfection he treated as independent of that of the active intellect and absolute. By treating each ‘intellect’ as requiring its own separate perfection, Aquinas concluded that, while the active intellect was perfected by acquired knowledge, the passive intellect was already independently perfected by a full influx of angelic species from the beginning. However, it seems to me that, given that we have not two intellects but one, requiring only one perfection that takes into account both aspects of the intellect, the single intellect can be said to have its proper natural perfection through the acquiring and concomitant receiving of species. Aquinas's philosophical notion of ‘relative perfection’, already employed by him with regard to the active intellect of the youthful Christ and extended above to his entire earthly lifetime, can now be further extended to encompass the passive intellect also. Like the active intellect, the passive intellect is properly perfected in the natural order step by step, and comes into existence not with an absolute perfection independent of that of the active intellect, but at each moment in time is perfected relative to that moment in time. Of course this does not exclude further supernatural perfections of the intellect as are conducive to our salvation, such prophetic knowledge and even the beatific vision, which I shall treat in my forthcoming Did the Saviour See the Father? Christ, Salvation, and the Vision of God,Footnote 49 but it should give an account of Christ's human intellect that strikes us more readily as genuinely human rather than evocative of myth, and which fits the guiding soteriological principle of Aquinas's Christology.
