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The term synderesis (συντήρησις) refers to the natural or innate habit of the mind to know the first principles of the practical or moral order without recourse to a process of discursive reasoning. The notion was developed by Aristotle, who insisted that there must be a starting point for man's thought, and that the first truths that would serve as such could not be acquired, like other subsequent truths, discursively or demonstratively. Unwilling to accept skepticism or Plato's theory of innate ideas, Aristotle taught that the mind must have the potentiality to acquire fundamental truths with certitude and infallibility without having to reason to them. Though man does not possess such truths innately, he does possess an innate or natural habit for acquiring them as self-evident propositions, once he understands the terms involved. This teaching of Aristotle explaining man's knowledge of first principles in the speculative order was accepted by Saint Thomas Aquinas, and further developed to include explicitly the first principles of the practical order (see cognition speculative-practical; first principles).

Historical Development. The term synderesis is derived from the Greek τηρέω used by Homer to mean "guarding closely," and subsequently συντηρέω used by Aristotle in De plantis to mean "preserving, keeping closely." The actual term συντήρησις seems to be of a Stoic origin and to lack any definite connection with συνείδησις, the similar word of Stoic philosophy, designating insight into simple matters of common knowledge. The latter term was used also by Chrysippus to describe the consciousness of harmony with oneself, which he regarded as a properly human expression of the fundamental impulse to self-preservation in all living things.

Scintilla Conscientiae. The term synderesis was introduced to the West by Saint jerome as part of his interpretation of the four living creatures in the vision of Ezekiel (Ezekiel 1.10; Patrologia Latina, ed. J. P. Migne, 25:22). Jerome claims that most commentators use Plato's tripartite division of the soul (into the irascible, concupiscent, and rational parts) to interpret three of the creaturesthe lion, the ox, and the man respectively. Over and above these there is also the eagle, which for Jerome represents what the Greeks call συντήρησις or "spark of conscience" (scintilla conscientiae ). This spark was not lost by original sin, and even though we abandon ourselves to passion or appetite, it enables us to know we are doing wrong.

Saint Jerome's phrase, scintilla conscientiae, found greater vogue among medieval scholastics than the term synderesis. The first to note the above-mentioned text of Saint Jerome was peter lombard, but he did not speak of synderesis. The term itself was used by a Master Udo in what seems to be the first commentary on Lombard's Sentences (c. 116065), where he identified it with reason and held that it cannot sin or consent to evil. Apart from these, simon of bisignano identified synderesis with natural law; peter of poitiers, with natural reason. The latter distinguished natural reason from deliberating reason on the basis that deliberating reason can consent to sin, while natural reason reacts against evil and inclines man to the good. A more extensive treatise was composed by stephen langton, who considered synderesis to be a natural tendency that protests against evil and inclines to the good; it itself is responsible for neither good nor evil, is superior to deliberating reason, and is concerned only with generalities.

Later Scholastic Views. The concept of synderesis as a simple habitual potency originated with alexander of hales in his Summa Theologica. His idea was taken up and developed by Saint bonaventure, who placed the habit of synderesis in the will. Synderesis is to the will, he claimed, as judgment is to the reason. By nature man possesses a twofold source or aid to right living: conscience in the intellect to judge rightly, and synderesis in the will to dissuade from evil and stimulate to good. Thus, according to Bonaventure, synderesis is the original moral tendency of the will.

Saint albert the great and Saint thomas aqui nas both taught that synderesis belongs not to the will but to the intellect. Albert, however, regarded it as the rational faculty endowed with the habit of first principles of the natural law, whereas Aquinas regarded it as an innate habit of practical reason (not a faculty itself), by which man comes to know immediately the first principles of the moral order.

The Oxford masters exploited Augustine's theory of illumination in connection with synderesis. Most notable among these was robert kilwardby, who held that synderesis is man's participation in God, the eternal light, present in and communicating Himself to the soul, there serving as the norm of man's judgments and the efficient cause of his moral life. It is also noteworthy that duns scotus disagreed with Bonaventure and placed both conscience and synderesis in the practical reason.

Synderesis and Understanding. Some contemporary writers hold that Aquinas distinguishes two habits for grasping principles immediately: understanding for speculative principles, and synderesis for practical principles. Others hold that he allows but one habit of first principles. In this view, when the intellect grasps being as true, it apprehends the first rules of speculative thought, whereas when it grasps being as good, it knows the first rules of practical thought. Yet both sets of principles are known as true, and it is accidental to the functioning of the intellect that the latter are also known as good. This view thus identifies synderesis with understanding, stating in substance that a single intellectual habit, called understanding in the speculative order, is called synderesis when concerned with first principles in the practical or moral order.

As identified with, or similar to, the virtue of understanding, synderesis possesses this virtue's basic characteristics. Synderesis is therefore characterized, first of all, by the simplicity and immediacy of its operations. The principles attained by the intellect are so true and plain in meaning that they are accepted and used by all human beings, as soon as they are needed, even by a child.

Secondly, synderesis is natural, in a twofold way: first, in that it differs from a supernatural or infused habit, and secondly, in that its principles are obtained naturally, not through teaching or experimentation. The human intellect requires principles that are naturally known as a starting point for reasoned knowledge. Such first principles are not themselves natural or innate, but like all intellectual knowledge, have their origin in sense experience; yet man does have an innate or natural capacity to grasp their truth once he understands the concepts presupposed to their judgment. As a natural or innate habit, synderesis is possessed in equal degree by all men. Just as human nature is equally shared by all, so the principles attained by synderesis are self-evident to all. Nevertheless, one man may have greater insight into their meaning than another, if he has greater capacity of intellect; this in turn will depend upon the state of refinement of his internal and external sense powers (see senses).

Finally, synderesis is infallible. The human intellect cannot err regarding first and indemonstrable principles. A person whose intellect simply is not functioning, or is demented, or who has had physical injury to organs necessary for the exercise of his external and internal senses, will not of course come to know even these principles. But to speak otherwise of error with respect to such principles would be to remove the necessary basis for all ethical reasoning. Synderesis, then, is a natural capacity of man's mind, disposing him to grasp immediately and infallibly the truth of first principles in the moral order.

Relationship to Natural Law. The judgment forming a first principle must be so elementary that it will be seen as true as soon as the intellect understands the terms involved. Since the most general concept inducing man to action is that of the good, the first principle in the practical order must be: Good is to be done (with its necessary complement: Evil is to be avoided). This is therefore the basic principle for natural moral law. Following immediately from it, and thus known also by synderesis, are the simple or primary precepts of the natural law: A being must act according to its nature, a reasonable being must act reasonably, etc. The natural law prescribes those acts that are morally good for man, i.e., in accord with his natural inclinations: namely, in common with all living things, to maintain his life; in common with animals, to ensure continuation of his race by reproducing and caring properly for offspring; then, properly as human, to pursue truth, exercise freedom, and cultivate virtue. These are the basic natural inclinations of all men, at all times, everywhere. However, man's understanding of them increases with experience and with intellectual development. (see natural law.)

Synderesis and Conscience. Synderesis is a habit, while conscience is an act of judgment. Synderesis assures possession of the most general and universal knowledge of first principles of the moral order, whereas conscience is concerned with particular applications, i.e., with the practical reasoning that provides answers to particular moral problems.

Man explicitly or implicitly uses a kind of syllo gism in his acts of choice, and thus descends from universal principles or premises to particular moral conclusions. In this reasoning process synderesis provides the most universal moral principles, such as: Every evil is to be avoided. Reason supplies more specific and less universal precepts, adverting to the cause of a command or prohibition, such as: Adultery is evil, because it is against the law of God, or because it is unjust. Conscience then reaches the conclusion: Adultery should be, or should have been, avoided. (It may be noted that while synderesis is infallible, conscience can err in the process of reasoning.) This judgment of conscience then becomes a proximate principle for human action. Both synderesis and conscience, then, furnish norms for action: synderesis, by providing the most general and universal principles; conscience, by providing the immediate and particular reasoned judgment about a moral act.

See Also: human act

Bibliography: thomas aquinas, Summa Theologiae 1a, 79.1213; 1a2ae, 94.12; In 2 sent. 24.2.3, 39.3.1; De ver. 16.13. r. eisler, Wörterbuch der philosophischen Begriffe, 3 v. (4th ed. Berlin 192730) 4:199200. o. lottin, Psychologie et morale aux 12 e et 13 e siècles, 6 v. in 8 (Louvain 194260) 2:101349. j. w. yedlicka, "Synderesis as Remorse of Conscience," The New Scholasticism 37 (1963) 20412. j. pÉtrin, "L'Habitus des principes spéculatifs et la syndérèse," Revue de l'Université d'Ottawa 18 (1948) section spéciale 20816. j. deblic, "Syndérèse ou conscience?," Revue d'ascétique et de mystique 25 (1949) 14657. j. rohmer, Dictionnaire de théologie catholique, ed. a. vacant et al., 15 v. (Paris 190350) 14.2:299296. o. renz, "Die Synteresis nach dem Hl. Thomas von Aquin," Beiträge zur Geschichte der Philosophie und Theologie des Mittelalters 10.12 (1911).

[m. w. hollenbach]

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