SYNDERESIS, a term in scholastic philosophy applied to the inborn moral consciousness which distinguishes between good and evil. The word is really synteresis (Gr. OWTI^HJO-IJ, from avvrtipeiv, to look after, take care of), but synderesis is the commoner form. Diogenes Laertius in his account of the Stoics (vii.Ss, rf/v 51 irpurtiv bpni\v <t>aai rf> fcpov la-xfiv iirl r6 r^pitv lavrti) uses the phrase Tt\p(.v tavrb to describe the instinct for self-preservation, the inward harmony of Chrysippus, the recognition of which is avvfldijais. The term synderesis, however, is not found till Jerome, who in dealing with Ezek. i. 4-15, says the fourth of the " living creatures " of the vision is what the Greeks call OWT^PTJOIS, i.e. scintilla conscientiae the " spark of conscience." Here apparently synderesis and conscience (oweiSTjcrts) are equivalent. By the schoolmen, however, the terms were differentiated, conscience being the practical envisaging of good and evil actions; synderesis being, so to speak, the tendency toward good in thought and action. The exact relation between the two was, however, a matter of controversy, Aquinas and Duns Scotus holding that both are practical reason, while Bonaventura narrows synderesis to the volitional tendency to good actions.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)