The human soul is the substantial form of the human being, coming into existence as part of a matter-form composite (DEE, chaps. 2, 5). The soul (termed ‘‘intellect’’ in its function as the principle of intellectual operation) can grasp the essence of material entities; hence intellect is immaterial, since a particular material configuration would impede such knowledge. Moreover, though knowledge originates with sensation (see below), intellect acquires its concepts through an activity that is proper to it, and thus intellect functions apart from matter and is subsistent, for whatever acts must be in actuality (ST Ia.75.2). Since it subsists, soul survives the death of the body, undergoing an interim of reward or punishment (SCG IV.91), after which the soul is reunited with its body in the Last Judgment (SCG IV.79, 96). Nonetheless, while separate from body, soul lacks the organs necessary for it to perform its proper function, which is to know sensibles. Hence it is contrary to soul’s nature (contra naturam) to subsist in this way (SCG IV.79.10) (cf., In DAIII.5.745).
Awareness of an extramental essence begins when our external senses transmit impressions of some extramental entity x in the form of sensible species, described by Aquinas as immaterial representations of extramental objects (In DA II.24.553). The internal sense dubbed phantasia transforms these sensible species into an internal representation of x, termed a ‘‘phantasm,’’ by means of a modification of some bodily organ (ST Ia.85.1c, ad 3). Aquinas’ account suggests that it is through this representation, not the sensible species, that we initially become conscious of extramental entities. Thus far, perception is a physical phenomenon, accounted for by various internal and external organs; but after the generation of a phantasm, the intellect begins its work. First, the aspect termed ‘‘active intellect’’ extracts from the phantasm an intelligible species, which conforms to the essence or quiddity of x (ST Ia.84.7), but not as the form of any particular entity. Thus an intelligible species prescinds from material considerations or physical representations such as are given through the phantasm (ST Ia.85.1, ad 3); nonetheless, as its attending to phantasms is a necessary condition of the active intellect’s production of an intelligible species, the intellect grasps the essence as one that exists in matter. This non-eidetic grasp of the essence or quiddity on account of which an extramental entity falls under certain genera and species is then stored in what is termed the ‘‘possible’’ (or, more loosely, ‘‘passive’’) intellect, allowing us to retain our concept and hone it through further investigation (ST Ia.79.2, ad 2; 85.5c).
Aquinas believes that human beings are free, though they necessarily desire the good. He develops this position in light of a discussion of four types of necessity corresponding to Aristotle’s four causes (ST Ia.82.1). Natural necessity arises from internal material and formal principles. Thus, a substance composed of contraries is necessarily corruptible (material) and the interior angles of a triangle necessarily equal 180° (formal). By contrast, necessity of the end emerges because of something extrinsic, such as food required for living. Finally, necessity with respect to coercion obtains when an action is compelled by some external agent. Only this last type of necessity is incompatible with free will.
That we desire the good is a natural necessity, underlying all action of the will in the way the principle of noncontradiction governs the speculative intellect (ST Ia. IIae.94.2c). Since we naturally desire the good, we are, on occasion, subject to necessity of the end, because there may be only one way to acquire the good we desire. That this second type of necessity does not preclude free will seems clear enough; we would not ordinarily say that a person who chooses to go on a journey lacks a free will because he must book a flight. However, it may seem that natural necessity robs the will of its freedom. Aquinas’ response emerges in his discussion of intellect and will.
Will is an appetitive power, naturally moved by its object, which is happiness (ST Ia.82.1c). Aquinas distinguishes between intellectual and sensitive appetitive powers, classifying the will as intellectual owing to its reliance on intellect, which conceives the good that moves the will (ST Ia.82.3, ad 2). More specifically, the will is moved by particulars conceived as standing under universal types, as one is moved to hatred or desire when conceiving some particular under the type thief or good, respectively (ST Ia.80.2). The good conceived by intellect is an unmoved mover acting on will through final causality, while the will itself acts as an efficient cause with respect to diverse faculties, setting them in motion to attain the desired end (ST Ia.80.2). Though intellect initially sets will in motion through intellect’s apprehension of a particular under a universal, will’s efficient causality extends to intellect (ST Ia.82.4). Finally, we may note that intellect does not generally present will with only one cognized good; instead, intellect furnishes will with a variety of goods among which will is free to choose (ST Ia.82.2, ad 3). This, coupled with will’s ability to direct the intellect to consider even more goods, or the same goods under different aspects, accounts for freedom of will. Though oriented to the good, when presented with a variety of goods, will is free to choose which to pursue.
World History
