An Explanation of Thomas Aquinas’ Doctrine of Synderesis

All theories of ethics must answer the question, “Is moral knowledge possible?” The major division of theories of ethics into non-cognitivist and cognitivist categories reflects how each theory answers this question. All non-cognitivist theories (those theories which according to van Roojen, have two claims in common: 1. “Predictive moral sentences [do not] express propositions or have substantial truth conditions;” and 2. “States of mind conventionally expressed by moral utterances are [not] beliefs or mental states which fall on the cognitive side of the cognitive/non-cognitive divide”) imply that moral knowledge is impossible.[1] This is true for the following reasons. First, non-cognitivists deny “the cognitivist claim that moral judgments are capable of being objectively true, because they describe some feature of the world.”[2] Second, “if moral statements cannot be true, and if one cannot know something that is not true, [then]…moral knowledge is not possible.”[3]

All cognitivist theories, on the other hand, hold “that moral statements do express beliefs and that they are apt for truth or falsity.”[4] Underlying this position for all cognitivist theories except error theory,[5] is the moral realist belief that there are moral facts or properties in our world and that we are able to hold “justified true moral beliefs,” or have knowledge, concerning them.[6] Among these cognitivist theories which hold out the possibility of moral knowledge are Eudaimonism, Natural Law, and Virtue Ethics, three related theories that are of particular interest to Christians.[7]

Given the significance of the question of the possibility of moral knowledge to the success of cognitivist moral theories, it is in the interest of the eudaimonist, natural law theorist, and virtue ethicist to offer and defend some account of the possibility of moral knowledge. In this article, I will offer and defend a Thomistic explanation of the possibility of moral knowledge which is consistent with and/or incorporated in eudaimonistic, natural law, and virtue ethics theories. I will do this by explaining Aquinas’ doctrine of synderesis in four points and by noting an advantage of Aquinas’ doctrine of synderesis over a competing Platonist, realist view.

Aquinas’ Doctrine of Synderesis

Aquinas’ doctrine of synderesis arises from the work of a several earlier thinkers. According to Langston, the seeds of the discussion of synderesis can be traced back to Plato’s Protagoras and his Meno, and to Aristotle’s Nicomachean Ethics.[8] Hoffman notes that the use of the term synderesis proper finds it beginning with Jerome and his commentary on Ezekiel.[9] There Jerome related the view of another thinker which he disagreed with, possibly Origen’s.[10] Jerome’s text raised several philosophically fruitful questions including: “Is synderesis a faculty or a habit? Is it cognitive or affective? Is it infallible? What is its relation to conscience?”[11] Among the thinkers who addressed these questions in subsequent centuries were Augustine, Albert the Great, and Bonaventure, the latter making an important contribution to Aquinas’ thought by dividing synderesis and conscience into two separate faculties of the mind, something which previous thinkers had not explicitly done.[12]

So, what is synderesis? Budziszewski offers the following helpful definition: “Synderesis…is the natural and habitual knowledge of the first principles or starting points of practical reason.”[13] From this definition we should note, first of all, that synderesis is a “habit” in sense that Thomas uses the term, a “disposition that enables us to do something.”[14] More specifically, synderesis is a habit of the practical intellect by which we discover the principles or precepts of the natural law.[15] It can be thought of as an “in-built tendency by which reason is able to declare” the ordinances of the natural law.[16] Synderesis can be called a “habitual knowledge" in that it is claimed of synderesis that it results in actual moral knowledge.[17] Describing synderesis as one of the habits of one of the powers of the soul and not a power itself, J. Budziszewski notes:[18]

Synderesis is a natural tendency of one of its powers – it is the natural disposition of human reason to understand the starting points of human action, such as the indemonstrable first principle that good is to be done and pursued and that evil is to be avoided.

Here Budziszewski is making the distinction Thomas makes—synderesis is not a separate power of the soul but a habit of one of the powers of the soul, namely, reason. To this point, Aquinas says:[19]

Thus, just as there is a natural habit of the human soul through which it knows principles of the speculative sciences, which we call understanding of principles, so, too, there is in the soul a natural habit of first principles of action, which are the universal principles of the natural law. This habit pertains to synderesis. This habit exists in no other power than reason, unless, perhaps, we make understanding a power distinct from reason. But we have shown the opposite above.

A second important fact about synderesis is that it is, according to Thomas, habit of reason by which we come to know the basic moral facts of our world. As Aquinas sees it, and I agree, there must be some set of indemonstrable first principles of practical reason in the same way that there are certain indemonstrable first principles of speculative reason like the law of noncontradiction. These principles, like those of speculative reason, may serve as the foundation or basis for additional knowledge, in this case, moral knowledge. Hoffman explains,[20]

Synderesis is the “natural habit” of reason containing these first practical principles, which means that by nature each human being has a fundamental awareness of these principles and that they can be used promptly when needed. By positing first practical principles as the foundation for all moral thinking, Aquinas does not suggest that they are explicitly used as the starting points of all moral reasonings. They are rather tacitly presupposed and made explicit only upon reflection.

Notice, synderesis is that habit of reason by which we come to know the first principles of practical reason on which all other moral thought is based. Synderesis supplies us with a foundation of moral knowledge. This knowledge is often reduced to the simple statement that good ought to be done and evil ought to be avoided. As examples of the kinds of principles that are in our foundation through synderesis, Aquinas suggests the following: “evil is to be avoided,” “nothing illicit is to be done,” “God is to be obeyed,” and “one must live according to reason.”[21] Describing the moral knowledge that comes by synderesis, Budziszewski optimistically says “All of the precepts of the Decalogue are knowable either as first principles, or as proximate implications of the first principles.”[22]

In connection with this foundationalist claim is a third important fact, Aquinas claims that synderesis is infallible. According to Thomas, it must be the case that the knowledge provided by synderesis is infallible, otherwise we would not be able to be certain in our ethical beliefs (Aquinas believes we must be able to be certain in moral beliefs). Aquinas says:[23]

As a result, for probity to be possible in human actions, there must be some permanent principle which has unwavering integrity, in reference to which all human works are examined, so that that permanent principle will resist all evil and assent to all good. This is synderesis, whose task it is to warn against evil and incline to good. Therefore, we agree that there can be no error in it.

Thomas’ claim that synderesis is infallible aids in making an important distinction: synderesis is not the conscience. Whereas synderesis is infallible, the conscience, that habit of reason whereby we apply the moral knowledge arrived at by synderesis, is not. We may err in conscience, but we may not err in synderesis.

A fourth fact concerning synderesis that comes along with this distinction is that though synderesis is not the conscience, the conscience is informed by synderesis. Budziszewski notes, “Conscientia, conscience in action, is the actualization of this latent knowledge – the act of judgment by which we bring it to bear upon a particular deed.”[24] Hoffman explains,[25]

Conscience is the application of moral knowledge to a specific situation. This application has a syllogistic structure. The major of the practical syllogism is obtained from synderesis, the minor is administered by practical reason, and the conclusion is the dictate of conscience.

The following are examples of how synderesis and conscience work together to produce moral judgments:[26]

1. Nothing prohibited by God’s law is to be done. (major premise supplied by synderesis)

2. Intercourse with this woman is against God’s law. (minor premise supplied by practical reason)

3. I should abstain from intercourse with this woman. (dictate of conscience)

Or

1. The good is to be done. (major premise supplied by synderesis)

2. It is my marital duty to have intercourse with this woman. (minor premise supplied by practical reason)

3. I should have intercourse with this woman. (dictate of conscience)

To summarize, according to Aquinas, synderesis is that habit or disposition of reason by which one discerns moral facts in the world, the precepts of the natural law. This habit infallibly provides foundational facts for practical reason. As such, it serves as the raw material of the conscience, supplying the major premise of practical reason from which the dictates of conscience can be derived. With these things in mind, we might ask why we should take a Thomistic view of moral knowledge instead of some other view, for example, a Platonist, realist view.

The Advantage of the Thomistic Doctrine of Synderesis over Plato’s Doctrine of Anamnesis

Plato’s doctrine of anamnesis which he sets forth in the Meno “holds that all learning is recollection, that everything we will ever learn is already in us before we are taught.”[27] As such, it is a doctrine of innateness, that is, it claims that moral knowledge is innate. We are born with it. Samet explains: “According to this view, perception and inquiry remind us of what is innate in us.”[28] By contrast, Aquinas’ doctrine of synderesis holds rather that we are not born with moral knowledge, but that we acquire it by synderesis through experience in the world. Here it seems that Aquinas’ explanation of how have moral knowledge has much to commend it over Plato’s view. Budziszewski writes,[29]

Where St. Thomas speaks of synderesis or deep conscience, Plato speaks of anamnesis or remembering. The former thinker holds that we are exercising a natural tendency built into the mind; the latter maintains that we are literally remembering something that we learned before we were born. Plato’s hypothesis has two great weaknesses. Not only does it require us to believe that the soul existed before the present life, but it also leaves obscure how the soul learned in that life what it remembers in this one. For these reasons, St. Thomas’s hypothesis seems rationally superior.

Note, as Budzizewski reasons, Thomas’ view is superior because it does not require that we posit the pre-existence of the soul or any process by which the soul came to possess moral knowledge. Consequently, for cognitivists who wish to offer some account of how we come to have moral knowledge, Aquinas’ doctrine of synderesis is a more attractive option than Plato’s anamnesis.

Conclusion

Thomas Aquinas offers an account of moral knowledge in his doctrine of synderesis which is useful to the cognitivist, moral realist. His doctrine of synderesis holds that there is a habit of practical reason, synderesis, by which the mind is disposed to discern the basic moral facts of our world, what might be called the precepts of natural law. This habit of mind is shared among all human beings and is the font of the principles by which the conscience operates. Aquinas’ doctrine of synderesis is superior to Plato’s doctrine of anamnesis as it offers a natural explanation for the moral knowledge which we believe we have and from which we reason practically. As such, Aquinas’ doctrine of synderesis is useful to cogntivists including eudaimonists, natural law theorists, and virtue ethicists, who wish to offer an explanation for how they believe it is possible to have moral knowledge. If Thomas is right, we have moral knowledge and we can have certainty in our ethical beliefs and judgments.

[1] van Roojen, Mark, "Moral Cognitivism vs. Non-Cognitivism", The Stanford Encyclopedia of Philosophy (Fall 2018 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/fall2018/entries/moral-cognitivism/>. [2] Wikimedia Foundation. (2022, September 9). Non-cognitivism. Wikipedia. Retrieved December 7, 2022, from https://en.wikipedia.org/wiki/Non-cognitivism#:~:text=A%20noncognitivist%20denies%20the%20cognitivist%20claim%20that%20%22moral,noncognitivism%20implies%20that%20moral%20knowledge%20is%20impossible.%20 [3] Ibid. [4] van Roojen [5] On van Roojen’s description of non-cognitivism versus cognitivism, error theorists belong among cognitivists because they believe that moral statements express beliefs that are truth apt but which are just all false. [6] van Roojen [7] Carrasquillo, Romero. Lesson 7. PHE 610 – Ethics. [8] Langston, D. C. (2008). Conscience and other virtues: From Bonaventure to macintyre. Pennsylvania State University, 10-21. [9] Davies, B., &amp; Stump, E. (2016). The Oxford Handbook of Aquinas. Oxford University Press, 319. [10] Ibid. [11] Ibid. [12] Langston, 32. [13] Budziszewski, J.. Commentary on Thomas Aquinas's Treatise on Law . Cambridge University Press. Kindle Edition, loc 18324. [14] Ibid, loc 7322. [15] Ibid, loc 7322. [16] Ibid, loc 7360. [17] Ibid, loc 17061. [18] Ibid, loc 17211. [19] Thomas Aquinas: Quaestiones Disputatae de Veritate: English. (n.d.). Retrieved December 7, 2022, from https://isidore.co/aquinas/QDdeVer16.htm, a. 1. [20] Davies & Stump, 320. [21] Ibid, 320. [22] Is there a moral "sense"?: Http://undergroundthomist.com. Is There a Moral "Sense"? | http://undergroundthomist.com. (n.d.). Retrieved December 7, 2022, from https://www.undergroundthomist.org/is-there-a-moral-%E2%80%9Csense%E2%80%9D [23] Thomas Aquinas: Quaestiones Disputatae de Veritate: English. (n.d.). Retrieved December 7, 2022, from https://isidore.co/aquinas/QDdeVer16.htm, a. 2. [24] Budziszewski, loc 18324. [25] Davies & Stump, 322. [26] Ibid, 322. [27] Samet, Jerry, "The Historical Controversies Surrounding Innateness", The Stanford Encyclopedia of Philosophy (Summer 2019 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/sum2019/entries/innateness-history/>. [28] Ibid. [29] Budziszewski, loc 7246.