John of St Thomas on Distinctions in Aquinas
In his treatise on natural philosophy, the Renaissance scholastic commentator on Aquinas, John of St Thomas (more recently known as John Poinsot) offers this same distinction on the two uses of phantasia in the texts of his mentor, Thomas Aquinas:   
The concept phantasia should be taken in two ways.
- (a) One way is broader in scope and refers to each faculty of the internal senses, which make their own objects [phantasms]. The phantasia is distinct from the sensus communis and the external senses, which only know when they are impressed directly by the sensible objects. Thus, every internal sense except the sensus communis is referred to as the ‘phantasia’, which St Thomas uses in his Commentary on the Soul. [ . . . ]
- (b) Another way is when phantasia is taken as a term for the potentia imaginativa [i.e. vis imaginativa], which is a faculty distinct from the vis aestimativa and the memoria [ . . . ]
This position articulated by John of St Thomas corresponds to the structure and content of the analysis undertaken in this chapter.
In his discussion of medieval psychological theory, Leahey suggested that Aquinas ‘makes no original contribution to Aristotelian psychology’. It would seem, however, that the description of the internal sense organs and faculties found in Aquinas’s texts differs extensively from what Aristotle claimed in the De Anima. In discussing the role of each faculty of inner sense, Aquinas moves beyond the limits that Aristotle exhibited in the De Anima. Aquinas offers a distinction between the physiological place of the internal sense organs and the cognitive function of the faculties. In discussing the role of the faculty of an inner sense, he focuses attention on those inner sense powers that require a phantasm. Leahey’s interpretation, it appears, is without textual or structural merit.
While Aquinas writes that the sensus communis is not part of the phantasia when the phantasia is used as a generic concept, nonetheless the precise relationship and distinction between the phantasia and the sensus communis is not elucidated consistently by either medieval or early modern philosophers. For example, in his Liber Cannonis, Avicenna lists the phantasia as a faculty distinct and different from the sensus communis, which refers to that faculty of inner sense that retains the sensible forms after they have been conjoined by the sensus communis. This account is the same structurally as the one provided by Aquinas in the Summa Theologiae when he identified the phantasia with the imagination. On the other hand, in his De Anima,
Avicenna identified the phantasia with the sensus communis: ‘Of the hidden vital apprehensive powers, the first is the phantasia, which is the sensus communis. It is a power placed in the first concavity of the brain, receiving by itself all the forms, which are imprinted on the five senses and given to it.’ That there is a conceptual and logical inconsistency here is apparent. Establishing the structural and textual reasons for this distinction in Arabian philosophy of mind, however, is beyond the scope of this present inquiry.
In discussing Weinberg’s interpretation of Aquinas, the account of the internal senses that Wolfson ascribed to Aquinas should be noted. Wolfson’s essay agrees with the interpretation presented in this study, and he lists a fourfold classification of the internal senses for Aquinas’s philosophy of mind: ‘(1) Sensus communis, (2) imagination (phantasia sive imaginatio), both retentive and compositive, the latter only in man [sic], (3) estimation in animals corresponding to cogitation in man [sic] (aestimativa, cogitativa), (4) memory (memorativa)’. In addition, he list the five faculties of the internal senses which he claims Aquinas attributed to Avicenna. Interestingly enough, these are the very same five faculties of internal sense that Weinberg and Stump (the latter without reference to the vis cogitativa) attributed to Aquinas:
Referring specifically to Avicenna’s fivefold classification of the internal senses, Thomas Aquinas enumerates these as follows: (1) sensus communis, (2) retentive imagination (phantasia), (3) compositive human and animal imagination (imaginativa), (4) estimation or cogitation (aestimativa seu cogitativa), the former in animals and the latter in man, (5) memory (memorativa).
Given this discussion, it appears that Weinberg and Stump have attributed to Aquinas what Aquinas had indeed attributed to Avicenna. That this is a misunderstanding of Aquinas’s texts by Weinberg and Stump is clear. In referring to the influence of Avicenna on Thomas, Kenny too suggests: Aquinas believed that there were inner senses, and took over a list of them from Avicenna [ . . . ].’ While Aquinas never argued that the phantasia was a separate faculty of inner sense distinct from the imagination, nonetheless it is correct that some of his medieval predecessors did affirm this claim of separation—even his mentor, Albertus Magnus. In fact, as Wolfson has shown, nearly every medieval commentator on Aristotle devised his own position regarding the number and function of the internal senses. Appropriating Wolfson’s useful categories, Aquinas, utilizing his own version of Occam’s razor, combined the ‘retentive’ and the ‘compositive’ functions of inner sense into one faculty called the imaginatio or phantasia.
-  Aquinas, like his early 14th-c. scholastic successor, if possible did not multiply entities or sense faculties.
-  In his Sixth Meditation, Descartes also combines these two internal sense faculties.
-  Klubertanz’s monograph spells out these theoretical and textual differences in some detail.
-  John of St Thomas, Philosophia Naturalis, 4, p. 8, art. 2 (Reiser edn, III, 252b20-253a41). Deely, inhis commentary on this part of John of St Thomas (better known in Deely’s work as John Poinsot), suggests that possibly a distinction between sensation and perception is affirmed in this passage. This pointwill be developed later. In the judgement of this author, because of the distinction between the sensuscommunis and the vis cogitativa, Aquinas can affirm this distinction between sensation and perception.Deely’s study of John of St Thomas is particularly illuminating in his discussion of the role John playedin the maintenance of standard interpretations of Aquinas. See John N. Deely, New Beginnings: EarlyModern Philosophy and Postmodern Thought (Toronto: University of Toronto Press, 1994). See also Deely,Intentionality and Semiotics: A Story of Mutual Fecundation (Scranton, Penn.: University of ScrantonPress, 2007).
-  Wolfson notes (‘The Internal Senses, 97) that among the Arabian commentators, localization of theinternal senses within the brain caused disputes between the physicians and the philosophers.
-  Thomas Hardy Leahey, A History of Psychology: Main Currents in Psychological Thought (Harlow:Longman, 1987), 71.
-  Both Leahey and Kemp appear to blur this distinction between organ and faculty.
-  Avicenna, De Anima, as found in Klubertanz, The Discursive Power, 95.
-  Wolfson, ‘The Internal Senses’, 122.
-  Weinberg, Short History of Medieval Philosophy, 120-21.
-  Anthony Kenny, Medieval Philosophy (Oxford: Clarendon Press, 2005), 235; yet this may be but a slipof the pen (or the computer key, as the case may be), since Kenny lists only four internal senses and not thefive postulated by Avicenna.