Moving Beyond Empiricism: Intentiones Non Sensatae
This issue might be considered somewhat differently. Historians of medieval philosophy usually place the epistemology theory of Aquinas in the category of empiricism. This positioning normally signifies a contrast with any form of innate idea epistemology no matter how loosely connected with Plato’s theory of recollection. Every historian of philosophy knows that Aquinas assented to at least one epistemological principle central to empiricism: ‘Nihil est in intellectu quod non prius fuerit in sensu. ’ Obviously this is the standard textbook position on Aquinas’s epistemology. Although this empiricist characterization of Aquinas’s epistemology is acknowledged, nonetheless Aquinas postulates the intellectus agens with its abstractive function transcending the sensible particular and producing a conceptual awareness of essential or sortal properties. Through the intellectus agens, Aquinas provides the epistemological ground necessary to resolve Plato’s one/many problem. In the case of concept formation and the intentional awareness of the conceptual content of essential properties, Aquinas transcends the empiricism that is characteristic of later British and American philosophy, from Locke, Berkeley, and Hume to Mill, Ayer, and C. I. Lewis.
In addition to the intellectus agens, however, this chapter argues that there is another area of Aquinas’s epistemology that also transcends classical empiricism. This additional move beyond empiricism is neglected in contemporary writings both about medieval epistemology in general and Aquinas’s theory of perception in particular. An elucidation is needed of the concepts of ‘intentiones non sensatae’ or ‘species insensatae’. Moreover, these epistemological concepts apply to sense perception and not to the functioning of the intellectus agens. Even a rough translation of the above concepts— ‘intentiones non sensatae’ and ‘species insensatae’—indicates an awareness whose intentional content is not grasped directly by utilization of the external senses alone. In other words, these categories denote that a degree of intentional content is attained by some means other than direct sensation in the classical empiricist manner. Once again, the concept of some form of nativism is suggested. Aquinas established two faculties whose function on the sense level is to provide an awareness of intentiones non sensatae: the vis aestimativa and the vis cogitativa. The former is associated with brute animals; the latter is specific to human perceivers but is in some way analogous to the vis aestimativa. However, the exact nature of this awareness is not always spelled out clearly.
Given the textual evidence for the existence of cognitive structures denoted by intentiones non sensatae, the next question now concerns an elucidation of these concepts. Klubertanz argues in some detail that the intentiones non sensatae function of the vis cogitativa is similar structurally to the vis aestimativa. Thus, as the vis aestima- tiva is the faculty in brute animals through which the animal is able to discern the useful from the harmful, so too is the vis cogitativa in humans the faculty of inner sense that discerns the ‘good’, i.e. ‘that which is to be sought’ in specific situations. In other words, the vis cogitativa is that sense faculty which particularizes the maxim or first principle of the practical reason, which is ‘Good is to be done and evil avoided’. Put differently, according to Klubertanz, it is the function of the vis cogitativa to grasp here and now the particular good that is to be pursued. Klubertanz argues that the vis cogitativa puts the individual action to be undertaken under a general rule. Several accounts follow Klubertanz in limiting the intentional function of the vis cogitativa to actions about to be undertaken.  Mahoney argues, much like Klubertanz, that the vis cogitativa has its function closely aligned with the practical knowledge of the vis aestimativa5 This limited reading of the texts neglects the important account suggested by
Averroes and developed by Aquinas in his Commentary on Aristotle’s On the Soul, where the vis cogitativa is that faculty of inner sense that is aware of individual primary substances.57 In his several studies on the vis cogitativa, White too appears to place the vis cogitativa in the realm of human prudence and practical reason.58 While this practical function elucidated by Klubertanz, Kneale, Michon, White, and others might be a partial function of the vis cogitativa, nonetheless this faculty of internal sense plays an important function related specifically to Aquinas’s theory of perception.
In distinguishing sensation from perception, Aquinas offers an analysis much like what Reid proposed. In early modern philosophy, the term ‘perception’ ceased to have any clear meaning. This, to be sure, is not Aquinas’s account. Aquinas renders a distinction between sensation and perception, and this would entail that perception is not an ‘omnibus word, which Kneale suggested Hume had proposed. Although Aquinas does not make explicit the formal distinctions common to contemporary perception monographs, nonetheless the structure of his treatment suggests that this category difference between sensation and perception is a significant part of his epistemological realism.
De Principio Individuationis: A Neglected Aquinas Text
In addition to his Commentary on the Soul, in his De Principio Individuationis, among other texts, Aquinas indicates that the function of the vis cogitativa is to perceive an individual as an individual of a natural kind. An elucidation of this aspect of the vis cogitativa in De Principio Individuationis is necessary in order to account for this important cognitive and realist dimension of Aquinas’s epistemology. Historians of medieval philosophy, especially those interested in perception theory, have often overlooked this dimension. In De Principio Individuationis, Aquinas sums up nicely the issues under consideration in this part of the analysis.
However, the quiddity of a particular thing in its particularity does not fall under [is not seen as] a per se object for the exterior senses, because the quiddity itself is a substance and not an accident, nor does it pertain to the intellect as a per se object on account of its materiality. Therefore, the quiddity of a material thing in its very particularity is the object of the particular reason, whose task it is to confront particular intentions, and whose place in brutes is the natural aes- timative power. This power on account of its conjunction with the intellect—where is found the very reason which treats of universals—participates as a collective power; but because it is a part of the sensitive order, it does not completely abstract from all matter. Hence its proper object remains a quiddity of a material particular. That which falls under the particular reason this humanized rather than human faculty, we are inclined to think of it, as in the case of the estimative power, in terms of practical knowledge’: Cyrille Michon, ‘Intentionality and Proto-thoughts’, in D. Perler (ed.), Ancient and Medieval Theories of Intentionality (Leiden: Brill, 2001), 337.
is an individual [hoc aliquid] found in a material nature [per naturam materiae]; what falls under the external senses is through quantity. (De Principio Individuationis, ch. 2 (Parma edition), xvi; emphasis added)
Although some commentators on Aquinas suggest that the De Principio Individuationis is not an authentic work, that need not be of great concern here. The above passage ties together structurally and summarizes well what Aquinas claimed in his Commentary on the Soul. In the above passage, he affirms that the proper object of the vis cogitativa is a material thing, which is the primary substance of his ontology. This is a hoc aliquid. In addition, in other texts, he refers to the vis cogitativa as the ‘particular reason’ (ratio particularis). This is consistent with the text of De Principio Individuationis. Aquinas in turn probably owes this nomenclature to Averroes. Cajetan accepted the authenticity of this work, and also argued that a ‘singular substance according to quantified matter is known by the vis cogitativa’:
Substantiam particularem percipi a cogitativa [ . . . ] Nec loquitur de substantia in communi, sed de substanatia singulari [ . . . ] Ilud quidem de substantia individuali secundum materiam signatam quantitate: hoc autem de substantia ut habet modum essendi purae substantiae. (In Tertiam Partem Summae, q. 76 a. 7, in Klubertanz, The Discursive Power, 297, n. 6)
This passage provides evidence for the interpretation put forward in this analysis of the vis cogitativa. The individuated substance, the hoc aliquid, would be what Cajetan refers to as ‘hoc aliquid de substantia ut habet modem essendi purae substantiae’. This would be a primary substance, which is the individual of a natural kind existing here and now in rerum naturae. Klubertanz, however, is, to use a Wittgensteinian paradigmatic claim for philosophical stoppage: ‘trapped by a picture’. He holds that ‘sense is of the external accidents, while intellect penetrates to the interior of a thing, and attains the essence’. In one fell swoop, Klubertanz appears to render insignificant what Aquinas writes about the intentio insensata as applied to the vis cogitativa. Klubertanz is not alone in holding this interpretation, as this model appears all too often in the writings of twentieth-century Neo-Thomist historians of philosophy.
Cajetan’s position is the one defended in this study. In the end, Klubertanz suggests that the De Principio Individuationis is ‘doubtfully authentic’ and is to be considered only as ‘an experiment of St. Thomas’s in the direction of Averroes’. It is unclear where this point of Klubertanz takes us.
Since this passage from De Principio Individuationis is akin structurally to what Aquinas argues elsewhere, it is evident that in his theory of perception, he transcends the limits dictated by classical British empiricism. The hoc aliquid, the individual thing, is not just a collection of proper and common sensibles, what empiricists call a bundle of sensations or sense data. If this were the case, then the individual would be reducible to the collection of proper and common sensibles. Hence, it could be known through the external senses alone. There would be no need to postulate the vis cogitativa and the incidental object of sense. But Aquinas denies that such reducibility occurs.