Vis Aestimativa and Vis Cogitativa in Thomas Aquinas’s Commentary on the Sentences

1 On the topic of external sensation, see the still valuable article of G. van Riet, “La théorie thomiste de la sensation externe,” Revue philosophique de Louvain 51 (1953): 374-408. 611 The Thomist 76 (2012): 611-40 VIS AESTIMATIVA AND VIS COGITATIVA IN THOMAS AQUINAS’S COMMENTARY ON THE SENTENCES JÖRG ALEJANDRO TELLKAMP Universidad Autónoma Metropolitana Mexico City, Mexico I N THOMAS AQUINAS’S MATURE WORK, for instance in the Summa Theologiae or in the commentaries on De anima and De sensu et sensato, we find an elaborate discussion of the mechanisms of perception. In agreement with the Aristotelian tradition, Aquinas distinguishes five external senses, whose task it is to grasp and discern the essential sensibles, such as color and sound (sensibilia propria) and size, shape, and movement (sensibilia communia).1 Since this information about an object’s qualitative and quantitative features does not yet yield complete knowledge of the individual object, he posits according to the Aristotelian-Arabic tradition that animals have inner senses, which, based on the actual perception achieved by the external senses, compose and divide the information grasped. Aquinas calls this information intentiones, which roughly stands for those aspects of material, individual objects which are not directly apprehended by the external senses, as when a bird identifies a straw as a suitable object for building a nest. In addition to the five external senses, Aquinas distinguishes four different inner senses, which describe different ways in which sensible forms can be grasped. (1) The common sense (sensus communis) unifies the stimuli of external senses, while (2) imagination or fantasy (imagination seu phantasia) composes, divides, and stores those forms. (3) Memory and reminiscence JÖRG ALEJANDRO TELLKAMP 612 2 Although the notion of intentio is primarily introduced into the thirteenth-century philosophical discussion about perception and knowledge through Avicenna’sDeanima, I will not dwell on the Avicennian antecedent given the wealth of publications on this topic. See D. Hasse, Avicenna’s De anima in the Latin West (London: The Warburg Institute; Turin:Nino Aragno Editore, 2000), 127-53; D. Black, “Estimation (wahm) in Avicenna: The Logical and Psychological Dimensions,” Dialogue. Canadian Philosophical Review 32 (1993): 219-58. (memoria et reminiscentia) have the function of storing sensible forms insofar as they belong to the past and (4) vis cogitativa or vis aestimativa grasps the intentional content of those forms. The vis cogitativa is found exclusively in human beings, whereas the vis aestimativa of higher animals has an analogous function and occupies the same physiological space in the brain as the vis cogitativa. The latter is permeated with reason, but the former is not. The vis aestimativa explains the sensory processes achieved by higher animals, such as sheep and dogs, in virtue of the organic, material composition of their brain. The vis cogitativa, in contrast, is a cognitive function exclusive to human sensation, which has an organic component as well as an “immaterial” one, because it somehow participates in intellectual processes. This means that although both powers (vis aestimativa and vis cogitativa) are rooted in roughly the same part of the brain, that is, in the middle ventricle, they point at distinct forms of sensory experience, mainly because in human beings the participation with the intellect adds a rational ingredient which animals lack. Therefore, in Aquinas’s mature theory the vis aestimativa of higher animals and the human vis cogitativa are essentially different powers, which grasp sensible intentions either under the aspect of their practical relevance (vis aestimativa) or as particular instances that are perceived as being part of universal notions (vis cogitativa). Since the inner senses grasp aspects of material objects that are not perceived properly, that is, intentiones, a basic and brief account of this notion is required.2 Although it has a wide range of meanings in Aquinas’s thought, in the context of his discussion of perception and knowledge intentio stands, broadly speaking, for the cognitive content attached to an object, which encompasses VIS AESTIMATIVA AND VIS COGITATIVA 613 3 A thorough discussion of Aquinas’s theory of intentionality with regard to perception can be found in D. Perler, Theorien der Intentionalität im Mittelalter (Klostermann: Frankfurt, 2002), 42-60. 4 Aquinas...