Aquinas and the Natural Habit of Synderesis: A Response to Celano

Anthony Celano concludes his article on the foundation of moral reasoning in Aquinas by saying the following: “The flexibility and practicality of Aristotle’s ethics has given way to the universal codes of Christian morality.”^[1] Succinctly, he argues that given two traditions of moral reasoning – the Platonic and Aristotelian – ultimately a Platonic scheme is adopted by Aquinas and thus non-Aristotelian moral reasoning begins to enjoy primacy from the thirteenth century onwards. It is my contention in this article that Thomas does not adopt a system of moral reasoning based in the Platonic tradition, but rather extends Aristotle’s understanding of first principles from speculative to practical reasoning. As such, synderesis or the first principle of practical reasoning is the source rather than inhibitor of personal and spontaneous moral reasoning.

The beginning of this paper will outline Celano’s position. The second part will show that the thought of Thomas’ predecessors included a movement away from a strictly Platonic understanding of moral reasoning. In the third part I will detail Thomas’ thought on synderesis as a first principle of moral reasoning and show that he used it in a far more Aristotelian manner. My exposition of Thomas’ position will serve as an argument for how Thomas did not, as Celano argues, hold a view of moral reasoning that replaces Aristotelian, nature-based ethics with a system, “based upon the eternal immutable laws of a divine being.”^[2]

Part I: Celano’s Argument

Beginning with Plato and Aristotle, Celano delineates two distinct versions of moral reasoning:

The legacy of Platonic thought includes the idea that certain practices were eternally ordained by divine beings and are therefore universally binding. Another position, however, represented best by the works of Aristotle establishes moral excellence on the actions of the best citizens within a particular society.^[3]

He follows the thread of the first type of moral reasoning from Plato through Cicero and Augustine to the Scholastic authors. According to Celano the first tradition asserts innate universal principles as the means to gain certitude concerning moral actions. In contrast, the Aristotelian tradition exhibits a flexibility and spontaneity befitting reasoning about contingent matters: the reason of the experienced and wise man will be able to discern correct action by correct evaluation of the particular circumstances.^[4] Importantly, both Plato and Aristotle hold that this moral reasoning exhibits sufficient certitude: for Plato the inerrant principles provide certitude, for Aristotle the rightly-seeing wise man will see with certainty the correct course of action. Plato’s scheme falters when it comes to application: how are universal principles correctly applied in actual situations. Aristotle’s falters in generation: how does the wise man gain his wisdom without starting principles?

The next question Celano pursues is how the divergent Platonic and Aristotelian traditions of moral reasoning were received by the Scholastics. According to his study the term synderesis enters Scholastic discussions of moral reasoning by way of Jerome and takes the place of the innately given universal principles found in Plato. After tracing their thought Celano argues that it is ultimately the Platonic tradition of moral reasoning that takes precedence in the thirteenth century. His study concludes with the following evaluation of Aquinas’ position on moral reasoning:

In the moral theory of Thomas Aquinas the man of practical wisdom can no longer determine the best life to pursue, since the commands of natural law have been determined innately in every human being.^[5]

Thus in thirteenth century authors the freedom of Aristotle’s phronimos^[6] is restricted and the rectitude of moral action stems from the innately given, fixed principles of the divine law: “No human being can determine the relative importance of particular pursuits, since divine and eternal law command how all should act.” ^[7] However, the opposition of law against the freedom required for the development of true virtue is a false dichotomy. This is contrary also to Daniel Westberg’s view of Aquinas’ ethics where any polarization between virtue and law, “would be to give the erroneous impression that there is an inherent contradiction between law and virtue.”^[8] For Aquinas the discernment of the natural law is a human endeavor made possible by an innate human habit of synderesis which functions as the seed rather than inhibitor of virtuous development. It is the following view, then, presented by Celano that I wish to contest: that Aquinas adopted a distinctly Platonic brand of moral reasoning in which the principles are divinely given, inscrutable and inflexible rather than humanly derived and having their source in man’s nature.

Part II: Synderesis before Thomas

When Thomas speaks of synderesis he is speaking within a rich tradition that had already been working out the nature of this initially ambiguous power, faculty or habit. Synderesis is first mentioned in Jerome’s commentary on Ezekiel, and undergoes a series of interpretations before Thomas inherits it. In Jerome’s commentary^[9] synderesis is a fourth faculty above the tripartite soul of man. Medieval authors strove to interpret not simply what Jerome meant but to incorporate into their anthropology the presence of something in or attached to man that guarantees rectitude in moral reasoning. In tracing the tradition of moral reasoning Celano finds that Thomas follows the Platonic tradition of moral norms from universal principles. However, although Thomas does assert that synderesis is a habit of first principles, the tradition he is working within had already shifted to a more Aristotelian view of moral reasoning and Thomas, too, is innovative in furthering this shift.

The early commentators discuss synderesis as part of the rational faculty, but as part of the higher reason or ratio superior.^[10] Interestingly, one author, Alexander Neckham (d.1217) initially assimilates synderesis into the faculty of the will.^[11] This is of note because it is a recognition of the connection between synderesis and the appetible good. Later, however, Alexander assimilates synderesis into the rational faculty. What the early commentators reveal is a desire to subsume this fourth faculty into the traditional tri-partite division of the soul and not leave it, as in Jerome’s commentary, above and apart from the other three powers. Their interpretation implies that the part of man by which he determines what is morally correct is not something above him and inaccessible, mysterious, or irrational. It is not a blind force in the will outside the guidance or cognizance of human reason, but it is brought into the rational part of man. In these early articulations the aspect of man by which moral action is discerned is made proper to man. Rather than esoteric and indiscernible the truths of moral reasoning are accessible by man’s own power.

After these early commentators the first extended treatment of synderesis comes with William of Auxerre who retains the annexation of Jerome’s eagle into the tri-partite division of the soul, but rather than view synderesis as a part of the higher reason Auxerre simply makes synderesis higher reason itself. This strategy of making synderesis the higher reason turns it into something more contemplative than active. For Augustine the ratio superior directs the ratio inferior away from mutable goods to God. While it remains in man, the power by which good action is discerned is nevertheless only accessed by turning from action to contemplation and gaining insight on moral norms from immutable, divinely given truths. This scheme still resembles the Platonic tradition of moral reasoning insofar as the truth of right action is not gained by human reasoning but by seeking access to immutable truths.

By making synderesis the higher reason, however, the problem of the fallibility of reason emerged. In Jerome’s commentary synderesis has the unique place among the faculties of being inerrant, indeed it is synderesis which corrects the errors of the other faculties.^[12] In an attempt to solve this problem Roland of Cremona held that it is the ratio inferior or lower reason only that can err. William of Auvergne countered by making synderesis simply a function of the ratio superior: synderesis is that by which the natural law is known. As such, although synderesis cannot err, the rational faculty can. Note how far synderesis has migrated from its place in Jerome’s commentary: what started out as a fourth and separate faculty above the tri-partite soul is now a mere function attributed to one section of one of the parts of the soul. At this point, synderesis is not a faculty above man by which we act rightly without full knowledge, nor is it a power in man that he uses to gain access to inerrant norms of morality, but it is an inerrant tool or function reason uses to gain truth about moral action.

Philip the Chancellor takes up these questions regarding synderesis first by considering whether synderesis is a faculty or a habitus, which can be interpreted as asking whether synderesis is a fourth faculty, or whether it can be subsumed into the existing three. His second treatise considers the relationship of synderesis to reason especially in light of the four senses of reason.^[13] Philip formulates the terms of the question that characterize the way later authors detail with the subject: first, should synderesis be considered as a separate faculty, and if not, then what place does it hold within the tri-partite soul, namely within reason?

Subsequent authors discuss synderesis and moral reasoning in the framework laid out by Philip. Of the remaining authors preceding Thomas I will only discuss St. Bonaventure. Bonaventure adopts the Aristotelian division of practical and speculative reason and places the habit of conscience^[14] in the practical reason. The import of this move is weighty because it means that the truth about moral action is gained precisely by looking toward and not away from mutable circumstances: practical reason considers not eternal truths but the good of mutable human actions. The practical intellect is an extension of the speculative and no less concerned with truth than the speculative, but by adopting the Aristotelian division Bonaventure is able to assert that man can come to truth about right action by reasoning about mutable goods. With this move a clear shift has taken place: without abandoning the Platonic idea of truth through inerrant principles, Bonaventure has nevertheless moved the discussion of moral reasoning in an Aristotelian direction such that credence is given to moral truths gained by the human process of practical reasoning.

Thus by the time Thomas inherits the discussion of synderesis his predecessors have done much work to articulate how moral reasoning operates as an aspect of human nature. They have subsumed Jerome’s eagle-like faculty into the soul, thus moral reasoning is understood as an endeavor proper to man and not gained through access to divine immutable truths. Further, the part of the soul which considers moral action is the practical intellect, and thus moral truths can be gained from the mutable human condition.

Part III: Thomas on Synderesis

Thomas posits that synderesis is a habit of the practical intellect by which we know innately the first principles of practical reasoning and employs two arguments for his position. The first I will discuss in detail and then show how the second, which calls upon the idea of a hierarchy of being, is a legitimate correlative. As Michael Crowe details, Thomas’ treatment of synderesis recurs through his earlier works, such as his Commentary on the Sentences and the De Veritate, but I wish to focus on its more mature form in the Summa Theologiae. There, in ST I, Q. 79, on the intellectual powers, Thomas tackles the first issue posed by Philip the Chancellor: is synderesis a power? Thomas’ answer is decidedly in the negative.

The ordering of articles in ST I, Q. 79 is significant because Thomas unites many aspects of the intellectual power before treating synderesis in the twelfth article. Following the Philosopher, Aquinas distinguishes powers by their objects. He is thus able to unite the operations of reasoning and understanding in the same power (ST I, Q. 79 a.8) as motive and resting means, respectively, of attaining the object of truth. In article 9 he unites the higher and lower reason: it is through knowledge of temporal things that we move to knowledge of eternal things, nevertheless we know both eternal and temporal things under the same aspect of being and truth. The second unification is necessary for moral reasoning because the intellect must see how contingent events and actions relate to eternal consequences. The first unification is necessary to see that those ultimate ramifications are not understood immediately but require a process of reasoning which terminates in understanding. A corollary of this aspect of the intellect is that first principles, though innately known, are not known and understood immediately, but require the reasoning process to occur in order to be revealed.

Not only does Thomas unite several aspects of the intellectual power previously thought separate, he takes careful steps to argue that the intellectual power is proper to man. Thomas’ treatment of the intellect in ST I.79 can be viewed as a systematic argument for the intellect being proper to man. He shows that the soul is not intellect in its essence but has intellect as a power (1), he attributes both passive and active intellectual powers to man properly speaking (2–3), he asserts that intellect is in the soul (4), that it is something discrete and possessed by men individually (5), that memory is within rather than outside and distinct from intellect (6–7), that we gain truth through reasoning by means of our human intellect (8), that we understand immutable truth by means of our human intellect (9), that understanding or intelligence is an act proper to man’s intellect (10). We do not understand through participation in a higher intellect, or by recollection from participation in a previous existence, or by communal access to a single intellect. As such, when man reasons it is a human endeavor that takes place in time and universal truths are not innately given or immediately accessed: they must be reasoned to. As a habit of such an intellect synderesis for Thomas is a fundamentally human habit.

Towards the end of the question Thomas first details the distinction between speculative and practical intellect, and then treats of synderesis as a habit of the latter. While both speculative and practical intellect have truth as their object, they are distinguished because each directs the apprehended truth to a different end and this difference in ends is an accidental difference in the apprehended object: “Now, to a thing apprehended by the intellect, it is accidental whether it be directed to operation or not, and according to this the speculative and practical intellects differ” (ST I, Q. 79, a. 11). As Thomas mentions in his reply to the third objection, the practical intellect, just as the speculative, knows truth. The end of the practical intellect, however, is not being and truth simply as in the case of the speculative intellect, but being and truth extended to how we should operate in relation to them. As first principles allow us an inchoate knowledge of the end in speculative matters, a further principle is needed to provide an inchoate knowledge of the end in practical reasoning.

Thomas sees synderesis as the foundation for our knowledge of the extended end of practical reasoning. He moves from discussing the intellect as speculative and practical to discussing synderesis as habit of the practical intellect that is the habit of first principles and functions as the analogue to the first principles in speculative matters: “Wherefore the first practical principles, bestowed on us by nature, do not belong to a special power, but to a special natural habit, which we call ‘synderesis’” (ST I, Q.79, a. 12). Thomas is careful to reinforce the fact that this habit is proper to man and not externally attained: it is bestowed by nature, it is a special natural habit, it is “not a power, but a natural habit.”^[15] Roughly, then, synderesis is a natural habit in man that allows him to reason correctly to the end of what he should do. It does not allow us knowledge of the means – that is the work of prudence – nor a precise knowledge of the end, but provides knowledge of the end in some way.

That definition raises a series of questions, most importantly how such a habit works. Thus far I have omitted mentioning the phrasing of the principle of synderesis in order to focus attention on synderesis as an operative habit. It is difficult to distinguish between habitually held knowledge, formulated as a principle or proposition, and the habit by which we hold continually that knowledge. The first principles of speculative reasoning provide the analogues to understanding how a principle and its corresponding habit are interrelated.

In speculative matters the first principles are stated premises which we employ in a syllogism, but also imply the habits by which our intellect operates. They are both ‘in the background’ and form part of the syllogism itself. In the first way, in order to begin reasoning, it is necessary to tacitly hold the principle of non-contradiction: if I did not innately know that something cannot be both white and black at the same time and in the same respect, I would never begin to reason about whether the object is black and white, because I could not hope for a conclusion of any sort when ‘is’ has no concrete meaning. Similarly, syllogizing requires the tacitly held principle that what is in the whole will also be true in part. We are in the habit of holding the first principles in this way throughout the process of reasoning. They are the implicit foundation that allows us to begin reasoning because we trust that a conclusion is possible and are also that by which we confidently hold the conclusion. In this way the principles function as a habit and, although they must always exist, we only come to know them after they have been put to use tacitly in reasoning.

In another manner the first principles operate as principles, that is, they comprise the content of premises. To say, ‘snow is white’ is to say that that which is (snow) exists in a certain way (white) and cannot exist as, say, black, at the same time and in the same respect. In each of the premises of a syllogism the first principles are operative as content, albeit in a more specified manner. Take for example the simple syllogism, ‘all snow is white, this snowball is snow, therefore this snowball is white.’ Expanded, the syllogism runs as follows: ‘all part (snow) is related to whole (white), this part (snowball) is part of a whole (snow), therefore this part (snowball) is a part of the larger whole (white).’ The same may be done for the principle of non-contradiction. As such, the first principles of speculative reasoning operate as principles with content in the form of an explicitly stated principle. The principles imply a habit at work in order for the syllogism to proceed from premises to conclusion, but they operate as stated content of the premises. In order to operate as the stated content of the premises, they are specified in a self- -evident way: the proposition that “‘snow’ is a part” is self-evident in the syllogism and does not require, indeed cannot require, demonstration. Nevertheless, it is still a proposition that is reasoned to by means of knowledge of first principles: if I understand that ‘snow is’ it is self-evident from my knowledge of being as a whole that snow is a part of being.

The way Thomas reasons about the first principles of practical reasoning resembles the speculative process. We hold by the habit of synderesis the operative principle that describes the end of our operation: ‘do good and avoid evil’ and when we consider certain actions in relation to ourselves it is self-evident from our self-reflexive knowledge of our nature whether those actions are derivative from the first principle. It is these self-evident truths of operation that Thomas calls the natural law. This relationship will be clarified below. When Thomas speaks of the natural law, he uses the parallel between the way the first principles of speculative reasoning are held by means of a habit and the way in which synderesis is the habit by which we hold the principles of the natural law. In the response to ST I–II, Q. 94, a. 1 on whether the natural law is a habit, he first explains that it is not a habit properly and essentially because, “the natural law is something appointed by reason, just as a proposition is a work of reason.” There is, however, a second sense of habit: “Secondly, the term habit may be applied to that which we hold by a habit.” And in regard to this second sense Aquinas brings up the way in which the first speculative principles are held: “Thus in speculative matters, the indemonstrable principles are not the habit itself whereby we hold those principles, but are the principles the habit of which we possess.” Thus the nature of synderesis as a habit becomes clear: it is not the natural law itself, which is appointed or attained by reason, but it is the habit by which we grasp the natural law.

This description of synderesis, however, prompts a further question: what is the precise relationship of synderesis as a habit to the natural law? Vernon Bourke argues that the synderesis rule is a “formal principle with no specific material content”^[16] and unaided does not provide us knowledge of the content of good and evil.^[17] Bourke is right only in one sense because synderesis is a habit which functions as part of the practical reason and thus needs additional input to reach the propositions of the natural law. However, there is a real sense in which synderesis is a habit with content. In answering whether the natural law is a habit Thomas responds to the second objection, that Basil calls synderesis the law of our mind, and replies: “Synderesis is said to be the law of our mind, because it is a habit containing the precepts of the natural law, which are the first principles of human actions.” Given the above discussion, this description is confusing: how can synderesis, which is a habit by which we hold the principles of the natural law, also contain the precepts of the natural law?

Thomas’ thought on the matter is subtle and dispersed. The question as to how a habit can contain principles is raised in the Questiones Disputates de Veritate. Thomas devotes the seventeenth question to synderesis and in the fifth objection he raises this problem: nothing is inscribed in a habit, but only in a power. But the general principles of law are said to be inscribed in synderesis. In his response he distinguishes two ways in which something can be understood to be inscribed in another:

That something is inscribed in another is understood in two ways. In one way, as in a subject, and in this sense something can be inscribed in a soul only with reference to a power. In another way, as in a container, and in this sense there is no reason why something cannot be inscribed even in a habit. It is in this sense that we say the single elements pertinent to geometry are inscribed in geometry itself.^[18]

The comparison to geometry is effective, for one cannot conceive of geometry functioning without its elements, but the habitual use of those elements is also necessary throughout the working of propositions. Similarly synderesis is a habit that is in use throughout all moral reasoning from premises to conclusion and yet when considered as a stated principle contains within itself the specified content of the natural law. Daniel Westberg provides a good understanding of how synderesis functions in the practical syllogism saying that, “The first principle of practical reason remains the basic ground of all voluntary action, and all other principles may be taken as specifications of that principle.”^[19] By basic ground he means that it forms the content of the first premise and also remains operative throughout the duration of the process of practical reasoning.

Thomas speaks of this relationship between the synderesis and the principles of the natural law in ST I-II, Q. 94 a. 2, which asks as to the number of precepts of the natural law. In the body of the question Thomas first makes a distinction between what is self-evident because the terms of the propositions are known to all versus self-evident to the wise or learned only. Then he argues that what is apprehended by all is first being in the speculative and then good in the practical intellect which forms the ground for the first principle of practical reasoning:

Now as “being” is the first thing that falls under the apprehension simply, so “good” is the first thing that falls under the apprehension of the practical reason, which is directed to action: since every agent acts for an end under the aspect of good. Consequently the first principle of practical reason is one founded on the notion of good, viz. that “good is that which all things seek after.” Hence this is the first precept of law, that “good is to be done and pursued, and evil is to be avoided.

It is Thomas’ next stage of argument that is most compelling: he links the notion of the good as expressed in the first precept of law to a self-evident knowledge of the terms of what is good for man. In other words, what is good for man is not self-evident to the wise only, but is accessible to all who reason. In Thomas’ words, “all those things to which man has a natural inclination, are naturally apprehended by reason as being good, and consequently as objects of pursuit, and their contraries as evil and objects of avoidance.”^[20] In this way, by synderesis, the natural, habitual adherence to the principle ‘do good and avoid evil,’ the further principles of the natural law are seen self-evidently even by the simple through man’s knowledge of his inclinations.

Elsewhere Thomas gives reason for why this knowledge of the good is self-evident: there exists in us a good proportionate to the good of our final end by which we are inclined to act toward that end. In the question on faith in the De Veritate Thomas explains that:

Nothing can be directed to any end unless there pre-exists in it a certain proportion to the end, and it is from this that the desire of the end arises. This happens in so far as, in a certain sense, the end is made to exist inchoatively within it, because it desires nothing except in so far as it has some likeness to the end. This is why there is in human nature a certain initial participation of the good which is proportionate to that nature. For self-evident principles of demonstration, which are seeds of the contemplation of wisdom, naturally pre-exist in that good, as do principles of natural law, which are seeds of the moral virtues.^[21]

Thus, the principles of the natural law are self-evident to man because there exists in him a ‘certain initial participation of the good.’ The principles of natural law are self-evidently derived from the most basic principle of ‘do good and avoid evil’, not because man gains them from outside content or receives them directly from God, but because he looks within himself and is able to see through the good existing in his own nature the full goodness that is proportionate to him; he is able to see his end. In like fashion the seed has within itself the tree, within himself the child sees the man.

Thus synderesis is both the habit by which the practical reasoning operates and its first principle. We habitually both hold and employ the principle ‘do good and avoid evil’ but this principle is specified by further self-evident derivations, such as ‘self-preservation is good.’ These further specified principles of the natural law are always seen, because the predicate is self-evidently known from the subject. Equipped with the habitually held principle ‘do good and avoid evil’, the moral reasoner then inquires, “But what is the good that I should do?” The moral reasoner discovers by looking within herself inclinations to certain basic goods: preservation of self, species, and rational nature.^[22] Thomas holds that these inclinations are self-evidently derivable through both the habitually held principle of synderesis and the access each person has to his or her own inclinations. Put another way, if a bachelor was possessed of the habit to inquire after and remind himself of his marital status the habit would prompt him to perform a self-examination and he would immediately see that he is an unmarried man. The reasoning from ‘do good’ to ‘self-preservation is good’ appears less axiomatic. Thomas, however, argues^[23] that all men have access to this basic differentiation of the good for man, precisely because they have access to themselves and their own basic inclinations: the good has the nature of an end, and looking within ourselves we find certain basic inclinations that are tending to some end. Although we do not know where those inclinations will ultimately lead, as inclinations they nevertheless include an aspect of an end. It is our good that is the subject of the proposition and looking to our own inclinations as manifestations of our good we see self-evidently that our good is differentiated by certain basic inclinations: self-preservation, preservation of species, and rationality. Thus the predicates, or the natural law, are contained within the subject of the proposition as soon as the subject is known. The question of how a person becomes acquainted with these tendencies is another matter, but for current purposes it is necessary only to see that while the principles of the natural law are derived, the derivation is a self-evident one: once a person is acquainted with his or her own inclinations, no outside source is needed to reach the conclusions. For Thomas the first-person acquaintance with life as a human being is sufficient to see that ‘the good to be done’ self-evidently includes self-preservation. The salient point here is that the derivation of natural law from synderesis is emphatically not Platonic access to divine ideas. The derivation occurs because the habit of synderesis prompts us to examine it as a principle and from acquaintance with our own inclinations we see that the principle ‘do good’ differentiates according to three basic inclinations. Unlike access to Platonic divine ideas, access to these principles is had by basic self-knowledge.

Lastly, Thomas’ second argument for synderesis. The goods in man which Aquinas sees as being evidence of his proportionate end are the first principles themselves. For him, the first principles themselves are the seeds of contemplation in the speculative realm and the seeds of the moral virtues in the arena of practical reasoning. This role of the first principles sheds light on Thomas’ second argument^[24] concerning synderesis that makes use of the Platonic hierarchy of being: put crudely, Thomas argues that since, in the chain of being, there is overlap from one order of being to the next, there must be something in us that overlaps with the angels, and that something is synderesis. At first this seems a puzzling argument: it seems to place synderesis above and outside man… just like the Platonic ideas. However, since the first principles both in speculative and practical matters are for Thomas that initial goodness whereby we see our end in proportion to the initial existent good, it is fitting that those first principles are the highest part of us, the part which touches and overlaps with the angelic nature. Similarly, one might say that the highest perfection in a lion cub is its ability to play: this tendency is both a sign of the hunting prowess that will develop, while itself being the start and seed of that prowess.

Conclusion

For Thomas synderesis is that habit by which we hold the first principles of practical reasoning, which in itself self-evidently contains the principles of the natural law. Thomas’ language implies a mutuality, namely that synderesis is the habit that holds the principles, but also that the principles are inscribed in it as in a container. He himself has trouble expressing this enigmatic mutuality:

[...] it remains, therefore, that the name synderesis designates a natural habit simply, one similar to the habit of principles, or it means some power of reason with such a habit. And whatever it is makes little difference, for it raises a doubt only about the meaning of the name. ^[25]

Natural human reason works to conclude from the first principle “do good and avoid evil,” to what the content of that good is, but such reasoning is from subject to self-evident predicate and the terms are self-evident even to the simple because all, as human subjects, contain within themselves the inchoate knowledge of the good of human nature. This subtle interplay between an innately operative habit by which we reason from given precept to self-evident principles affords Thomas a position wherein the natural law is not a set of given commands, inscrutable and divine, but is a body of principles humanly derived. At the same time, however, each man has within himself a good proportionate to his final good by examination of the foundational principles he is able to reason self-evidently from that principle and his natural inclination to see what is good for human nature. Every human has the chance to be Aristotle’s phronimos.

Celano was correct to see that Thomas’ predecessors incorporate a Platonic idea of universal principles in order to account for rectitude in moral reasoning. However, although the tradition Thomas inherits certainly is borrowing elements from this Platonic framework, several authors had already begun to add their own genius to the problem of moral certitude in the changing situations of practical life. Bonaventure’s incorporation of Aristotle’s distinction between practical and speculative intellect allowed Thomas to operate within a framework that included both innately given principles but also a part in the intellectual power of man that dealt specifically with the ‘doable’ good which is mutable.

Thomas’ vision of the grounding of moral reasoning on innately given principles certainly resembles the Platonic line of moral reasoning laid out by Celano. However, Thomas’ exposition of the nature, origin, and functioning of that innately given principle is almost the antithesis of Platonic universal principles. For Thomas synderesis is an innately given principle, but it is given and not accessed by participation: from an intellect natural to man arises a habit of reasoning about practical matters that looks to man himself for its self-evident principles.