John Duns Scotus (the “Subtle Doctor,” 1265/66–1308 AD), in “Quodlibetum,” “Ordinatio” and “Quaestiones super libros de anima” outlines the process of human cognition:

• Cognition is based on sense perception of the material world, with corporeal organs as substrate. Objects in the external world generate sensible species in the sense-organs.
• Sensible species are further processed and stored in the internal senses (common sense, sense memory, and imagination). Phantasms are generated by the imagination based on sensible species.
• In abstractive cognition, the agent intellect abstracts common natures, universals from the phantasms, while intuitive cognition cognizes present singular objects.
• The possible intellect understands universals and present singular objects and generates discursive knowledge.

The following UML Use Case diagram presents Scotus’s model of the human cognition:

Use cases:

POWER	USE CASE	RELATIONS
5 EXTRERNAL SENSEs	(5 EXTERNAL SENSES) apprehend the sensible quality [sensible species] of an external object (UC1): “The simplest form of sensation, sensation per se, occurs when one of the five external senses apprehends the sensible quality that is its proper object: when sight sees color, for instance, or hearing hears sounds. Speaking more broadly, one sees darkness, or sees a human being. This is sensation per accidens.” (Normore, 2003) External senses are:  touch, sight, hearing, smell and taste
Common sense	(Common sense) distinguishes sensations and perceives what we sense [sensible species], and also time and magnitude (UC2): “the common sense is responsible for distinguishing different sorts of sensations from each other (sounds from sights, for example), and that it is responsible for perceiving that we sense. […] Scotus is happy to affirm, with Aristotle, that the common sense perceives time and magnitude—the common sensibles.” (Cross, 2014)	includes UC1
Imagination	(Imagination) stores and recalls sense images, sensible species in the absence of their objects; creates phantasms (UC3): “The imagination stores sense images in the absence of their objects, and is the faculty that recalls such images. […] As he sees it, the imagination conjures up things irrespective of their being past […] […] So there is a kind of sense cognition that is non-perceptual, and the phantasm is the relevant habit or species that allows for this kind of cognition. There is nothing surprising about this, since no one holds that imagination requires the presence of its objects, or that it is perceptual. The imagination is such that it can have acts whose contents are fixed by the phantasms: The phantasm … represents with its whole power the object as singular to the imagination (virtuti phantasticae), for there is then an actual imagination of that object in the singular.” (Cross, 2014)	includes UC2, UC4
Sense memory	Sense memory stores sensible species (UC4): “sense memory has the pastness of its objects attached to it in some way. […] the sense memory is responsible for remembering past sensations, and the objects of those sensations, as past. Scotus maintains that in this kind of recall the cognizer has the past act as her immediate object and the (sensory) object of that act as her remote object. So we have memory of the past as past by having memory of past acts of sensation. Scotus holds that there must be a species impressed by the past sensory act (to make the act relevantly, but of course not really, present to the subject). […] So the mechanisms of perception require sensible species. But Scotus holds that we have a number of sense operations that are not in fact perceptual: particularly, memory and imagination; and we have some dysfunctional sense operations too, such as hallucination. And, Scotus maintains, all of these require species. First of all, he holds that we need sensible species in order to account for sense memory: not in this case our memory specifically of past sensations, but our memory of the objects of such sensations. […] As we have seen, Scotus holds that there is a kind of sense memory—memory of past events as past—that requires that the past sensation is the immediate object of recollection” (Cross, 2014)
Agent Intellect	Abstractive cognition: (agent intellect) abstracts intelligible species, common natures, universals from phantasms (UC5): “Scotus holds, in good Aristotelian fashion, that there is an agent intellect, and that it is the faculty that (partially) causes intelligible species. […] the agent intellect is as a power for abstracting intelligible species from phantasms […] The object of abstractive cognition is (standardly) the common nature, but abstraction precludes existence and presence, and in so doing (it seems) basically excludes the individuating feature. Abstraction enables us to grasp the common features of a kind. […] The content of an abstractive cognition is a universal, a definition: it is a conceptualization of a common nature, sufficient to give some kind of account of such natures, and sufficient to ground the various general predications that we might want to make about kinds of thing.” (Cross, 2014)	includes UC3
Agent Intellect	Intuitive cognition: (agent intellect) cognizes present singular objects (UC6): “There is another act of cognizing, which, although we do not experience so evidently in ourselves, is possible. It is precisely of a present object, as present, and of an existent object, as existent. […] Given that existence is a necessary condition for real presence, it follows that intuitive cognition necessarily has the existent as its object. […] But a further distinction, between intuitive and abstractive cognition, follows from this, and we need to keep it in mind if we are to understand everything that Scotus says on the matter. I noted that the object of both kinds of cognition is the common nature; and I take it that Scotus would allow too the singular in the case of intuitive cognition, albeit falling short of de re cognition of the singular . But—crucially—the contents of each kind of act are different from each other. Intuitive intellectual cognition acquaints the cognizer with the object, though in such a way that the content of such a cognition can figure in syntactic complexes (to use Scotus’s example, ‘Peter is sitting down’). […] He holds that all propositional knowledge is intellectual, and he seems to suppose that the intellect’s forming contingent propositions about singulars (not, I take it, propositions about singulars de re) requires that all the relevant mental contents inhere in the intellect, not the senses Elsewhere, Scotus gives an example of the kind of thing he has in mind: the intellect can know that Peter is sitting down (sessio Petri), on the basis of which, presumably, it can form the contingent proposition ‘Peter is sitting down’: where the point of the discussion is that the intellect can form (tensed) propositions about ‘the present’, propositions whose contents are simply current perceptual experiences.‘” (Cross, 2014)	inludes UC2
Possible intellect	(Possible intellect) knows/understands intelligible species and present objects (UC7): “the possible intellect is the ‘intelligence’ the power for occurently cognizing, for ‘receiving the act of undestanding’. […] Since, according to Aristotle, again as interpreted by Scotus, the faculty that actually thinks, and that stores intelligible species, is the possible intellect, the possible intellect must include both memory and intelligence.” (Cross, 2014)	includes UC5, UC6, UC8, UC9
Intellectual Memory	Intellectual memory stores intelligible species and past intellective acts (UC8): “Scotus refers to the faculty responsible for storing intelligible species as the ‘memory’ (memoria), and he holds too that the memory is the relevant causal power that produces occurrent cognitions. […] The idea is that memory—the storehouse for intelligible species in humans causes, jointly with these species, occurrent cognitions. […] And the possible intellect is the ‘memory’ too, the storehouse for intelligible species and cognitive dispositions. Evidence for this comes from Augustine: scientia is stored in the memory, and the term here is used to refer to habitual cognitions— intelligible species. The point is that the presence of scientia brings it about that the intellect can occurrently cognize without any further change—it is in accidental potency rather than essential potency.” (Cross, 2014)
Intelligence	(Intelligence) thinks (UC9): “Following Augustine, at least as interpreted by Scotus, occurrent cognitions inhere in the intelligence, which is thus the power that actually thinks, or that has the relevant operation (or rather, the activity is the soul’s, and the memory grounds the activity […]). Scotus makes the point as follows, using Augustine’s terminology of the mental word to refer to an occurrent cognition: Therefore, the word can be described as follows: the word is an act of the intelligence, produced by perfect memory, existing only with an actual act of intellection. […] And from these things it is clear that the word pertains neither to the will nor to the memory (because it is the second part of the image, not the first or the third), and consequently it is not an intelligible species or habit, or anything that pertains to the memory. Therefore it is somethingthat pertains to the intelligence.” (Cross, 2014)

Actors:

Actor	Description	Relations
Object	A material object in the external world.	generates sensible species in the sense organs.
User of the soul	A human person.	uses UC7

Sources

• Normore, Calvin G., “Duns Scotus’s Modal Theory”, The Cambridge Companion to Duns Scotus, Cambridge University Press 2003, ed. Thomas Williams
• Cross, Richard, “Duns Scotus’s Theory of Cognition”, Oxford University Press, 2014
• Williams, Thomas, “John Duns Scotus“, The Stanford Encyclopedia of Philosophy (Winter 2019 Edition), Edward N. Zalta (ed.)

First published: 10/6/2021