[4.13.2] Peter Olivi on Perception, Attention, Cognition and Free Will

Peter John Olivi (ca. 1248–1298 AD) in Quaestiones in secundum librum sententiarum discusses the structure of the human soul, and aspects of sense perception, cognition, and free will:

  • He criticizes the Aristotelian conception of the soul’s knowledge-generating process (see [1.3.6]) because of its passivity. According to this model, the knowledge-generating process depends on the external objects. Olivi (as St Augustine) insists that perception and knowledge cannot be based on passive reception of external stimuli, but must be understood as active processes because the soul is ontologically superior over the body. He sustains that attention is the function that actively controls perception (see also Kilwardby’s similar model [4.12.2]).
  • Perception is realized in the common sense, not in the sense organs.
  • Common sense assures the phenomenal unity of a humans’ psychological acts, a faculty capable of performing a series of complex functions, like attentionestimationperception (see also Avicenna [3.3.3])sensitive memory, imagination, and cogitation.
  • He emphasizes the free will’s role as a principal function of the soul’s rational/intellectual part (see also [4.13.1]).

The following UML Use Case diagram presents Olivi’s model of the human soul:

Peter Olivi on perception, attention, cognition and free will
FACULTY/FunctionRelated Use CaseRelations
5 sense organs5 SENSE ORGANS impressed by object (UC1)relates to Object
COMMON SENSEPrecieves as one and distinguishes the object (UC2): “Olivi’s basic idea is that perception, understood as awareness of the object of sensation, requires that attention be directed towards the senses and their objects:
‘if my eyes are accidentally directed toward an object, but I am concentrating on some philosophical question, the object does not appear to me. Or, as Olivi remarks, if I am asleep or daydreaming, I do not perceive the objects that are before my eyes, even if my eyes are wide open: frequently, there are many passions in our senses that do not appear to us. This is patent when someone sleeps with his eyes, ears and nostrils wide open. Passions that take place in the senses are not then actual perceptions, even though they are specifically (secundum speciem) the same passions that take place in those who are awake.’ […]
There were two functions traditionally attributed to the common sense: it brought together information provided by the different external senses, and it discerned between objects of the different external senses. The first function explained the fact that we are able to perceive objects of the different external senses as one. For instance, when I see a frog and hear its croaking, I perceive the visible qualities (colour, shape) and the audible qualities (croaking) as belonging to the same creature.
Since my eyes cannot hear the croaking and my ears are not able to see the colour and the shape of the frog, the ability to combine these qualities must be attributed to a faculty that apprehends the information provided by both eyes and ears. This is the first basic function of the common sense.
The other basic function of the common sense was to distinguish between objects of the different external senses.” (Toivanen, 2007)
includes UC1; extends UC3
COMMON SENSE/AttentionFocuses attention on the object to be cognized (UC3): “Olivi’s basic idea is that perception, understood as awareness of the object of sensation, requires that attention be directed towards the senses and their objects” (Toivanen, 2007)
COMMON SENSE/ Estimation (potentia aestimativa)(Estimation) apprehends harmfulness and usefulness of objects (UC4): “Contrary to the traditional view, Olivi thinks that estimation can be explained by a special kind of apprehension of external objects. An estimative act of apprehension, brought out by the common sense, suffices to explain the apprehension of harmfulness and usefulness of objects. [,,,]
The common sense perceives the burning of the hand and apprehends that the fire is harmful to the hand and to the wellbeing of the child: the common sense estimates that fire is harmful. The child hopefully learns that one should not play with fire, and it is precisely this learning that is important, since only someone who has learnt that fire is harmful estimates it as such. How does this type of learning happen?
Olivi argues that there can be habitus in the common sense (or even in the external senses). When the child perceives that fire is harmful, the perception generates a habitus in the common sense, and this habitus affects the subsequent perceptions of fire.” (Toivanen, 2007)
includes UC2
COMMON SENSE/ Sensitive memory(Sensitive memory) retains objects and events as memory species of objects (UC5): “The next faculty that Olivi analyses is the sensitive memory, which is associated with two different functions. The first function is retaining apprehended things and events, so that they can be later recalled in the mind. […]
The memory does this by retaining so-called memory species (species memorialis), which are like images of external objects.” (Toivanen, 2007)
includes UC2
COMMON SENSE/ Sensitive memory(Sensitive memory) recalls memory species of objects (UC6): “The second function is recalling the retained things in the mind.” (Toivanen, 2007)includes UC5
COMMON SENSE/ Sensitive memory(Sensitive memory) recognizes known objects (UC7): “recognizing a present object as an object one has apprehended earlier.” (Toivanen, 2007)includes UC5
COMMON SENSE/ Imagination (potentia
(Imagination) apprehends absent objects (UC8): “The first function, i.e. to apprehend absent yet real objects, must be a function of the common sense, since apprehension is interconnected to the basic functions of the common sense. Olivi accepts that there is a phenomenal difference between apprehending present objects and absent objects: it is a different thing to perceive a frog, than to imagine one. However, Olivi does not accept that there is an ontological difference between the faculties. He stresses that we are normally able to notice a difference between perception and imagination:
‘For the act of discerning that an imaginary species is not an external object but something else, is nobler than just imagining the object. But the discernment happens through the common sense, because this [viz. the difference between an imagined and a real object] is discerned only while awake, and it takes place thus: the one who discerns, notices that the image of the absent objects is not situated outside the particular senses and neither is it apprehended by them.
Therefore, it is necessary that the very same power then compares the act of imagining to the acts of the external senses, and perceives and judges there to be a perceptible (sensibilis) difference between them. However, it is clear that to apprehend the acts of the senses – when they take place – and to make judgements of them, belongs only to the common sense. Therefore, to apprehend the acts of the imagination and to make judgements of them also belong to it. This is, to my mind, the most powerful argument among the aforementioned, because it is also proved by internal and frequent experience.’
Olivi’s argument is that the act by which we apprehend that an object is imagined, and not perceived, must be an act of the common sense. This is because only the common sense can apprehend whether the external senses are active or inactive. Some claimed that the faculty that makes this comparison is the intellect, but Olivi rejects this claim by arguing that animals are also able to make the distinction. Even though there is a henomenal difference between imagining an absent object and apprehending a present one, there is no ontological difference on the level of faculties: the same faculty, the common sense, which acts in both cases, performs both functions.” (Toivanen, 2007)
includes UC2
COMMON SENSE/ Imagination(Imagination) combines objects (UC9): “The other function commonly attributed to the imagination was that of combining retained species in order to make new ones. It was thought that at least human beings were able to imagine things they had never seen or perceived otherwise. Combining retained species explained the ability to imagine, say, a golden mountain. Olivi attributes this function to the common sense. According to him, only humans are able to merge species with each other and in that way imagine a golden mountain. This ability is denied to other animals, since they lack intellectual capacities. Reason can govern the imaginative operations, and when it does, two species can be apprehended together in a way that makes them appear as one species.
Characteristically, this view reveals that Olivi understands that the operation of the composition of species takes place in the active faculty, i.e. in the common sense. The species of a mountain and the species of gold are not actually merged but they both function simultaneously /442/ (or in such a way that there is only an imperceptible interval) as objects of an act of the common sense.45 The two species remain separate, but the act is directed at both, resulting in the imaginative act of a golden mountain. The argument, which Olivi uses to prove that imagining absent objects is a function of the common sense, is also suited to prove that composition of species belongs to the common sense.” (Toivanen, 2007)
includes UC8
COMMON SENSE/ Cogitation (potentia
(Cogitation) combines and compares information received from memory, estimation, imagination (UC10): “cogitation (potentia cogitativa) synthesizes all the information provided by the other four internal senses” (Toivanen, 2007)includes UC4; UC6; UC9
INTELLECTAbstractive acts produces concepts/words (UC11): “According to Olivi, concepts or words are not products of intellectual acts. A concept is nothing but the act by means of which the intellect selectively attends to the kind‐specific characteristics of an object, ignoring whatever individuating features it might have. In Olivi’s own words:
‘The first abstraction of universal characteristics occurs in the mere act of abstractive consideration of the real ratio of a common or specific nature without attending or considering the ratio of its individuation. But nothing objective that is different from the foresaid act of consideration is really abstracted or formed from this.’
It is my intellectual act itself that represents the kind‐specific characteristics of an object. In Olivi’s own words, when I selectively attend to the kind‐ specific characteristics of an object, these come to exist ‘intentionally or representatively in the act itself.’” (Adriaenssen, 2014)
includes UC10
INTELLECT/ Intellectual memory(Intellectual memory) retains memory species of concepts/words (12): “As we have seen above, Olivi believes that cognitive acts leave species in our memory just as signet rings leave their imprints on a piece of wax. For example, when I engage in a thought of John’s human aspect exclusively, a memory‐species pertaining to John’s human aspect is generated and subsequently stored in intellectual memory. When, after John has disappeared, I want to think of his humanity again (rather than of his individuality), I, as it were, return to this memory‐species. In Olivi’s own words, my initial thought of John’s human nature causes ‘some species in memory, which afterwards remains in us after the act of thought has ceased to be, and we return to it when afterwards we want to recall the things that we first intellectually considered as present in their absence.'”(Adriaenssen, 2014)Includes UC11
INTELLECT/ Intellectual memory(Intellectual memory) recalls memory species of concepts/words (13)Includes UC12
INTELLECT/Free will (liberum arbitrium)(Free will) initiates action (UC14) “Since Olivi thinks that the attitudes that distinguish us as rational creatures are founded on free will, giving up on free will would be to abandon most of what makes us human. We would cease to be what we properly are, persons, and we would become only “intellectual beasts […] Having proved that human beings have free will, Olivi sets out to explain what he means by freedom. His conception obviously belongs within the libertarian camp in the free will debate, and the central aspect of it is that in order to be free, the will must be active and capable of reflexively moving itself to action. True, the will’s choices are not necessitated by reason or anything other than by the will itself, but Olivi does not merely conclude that the will is not necessitated; the further conclusion he reaches is that the will, until it makes a choice, is entirely undetermined one way or another, and that it determines itself in the direction it chooses” (Pasnau, Toivanen, 2018)


  • Toivanen, Juhana, “Peter Olivi on Internal Senses”, British Journal for the History of Philosophy 15 (3) 2007: 427–454.
  • Adriaenssen, Han Thomas, “Peter John Olivi and Peter Auriol on Conceptual Thought”, Oxford Studies in Medieval Philosophy 2 (2014): 67-97
  • Pasnau, Robert and Juhana Toivanen, “Peter John Olivi”The Stanford Encyclopedia of Philosophy (Winter 2018 Edition), Edward N. Zalta (ed.)
  • Pasnau, Robert, “Olivi on the Metaphysics of Soul”, Medieval Philosophy and Theology 6 (1997), 109-132
  • J.F. Silva & J. Toivanen, “The Active Nature of the Soul,” Vivarium 48 (2010): 245–278.

First published: 25/2/2021

[4.12.2] Robert Kilwardby on Active Sense Perception and Cognition

Robert Kilwardby (ca. 1215–1279 AD), in De spiritu fantastico discusses the structure of the human soul and the process which leads from sense perception to cognition:

  • He sustains that the human soul is a composite of three forms: the vegetative (common in all living beings), sensitive (present in animals and humans), and intellective (specific to humans) (see also [4.12.1])
  • The powers of the sensitive soul are common sense, sensitive memory, while intellectual memory, intellect, and will are the intellective soul’s powers.
  • There is no knowledge of sensible objects without prior use of the senses, because the soul is completely empty before sensation.
  • The object present to the sense organ generates sensible species in the medium, which then changes the sense organ. For example, in the case of sight, the medium must be transparent, there must be light, and the object should be in the front of the eye.
  • The sense organ passively receives the sensible species from the objects of the surrounding environment, while the sensitive soul actively directs the attention on some of the sensible species; this is when perception occurs. Soul, through the act of attention, acts upon and controls the sense organ and not vice-versa.
  • Imagination creates images even than the object is not present; intellect abstracts universals from many images.

The following UML Use Case diagram presents Kilwarby’s model of the human soul:

Kilwardby on active sense perception and cognition
PowerRelated use caseRelations
Sense organSENSE organ is passively impressed by the sensible species of the object: “The affection of the sense organ (affectio organi) by the sensible species irradiated from the sensible object (ab obiecto sensibili). The result of this motion is the impression of the sensible species in the sense organ.” (Silva, 2013)
Common sense(Common sense) percepts likenesses of sensible species and apprehends the present object: “The soul involves itself with the species received in the sense organ (conuoluendo se cum illa), which results in the production by the soul of an image or likeness (similitudo) of the sensible species. According to Kilwardby, the sensory soul forms the image by natural instinct (instinctu naturali). Perception is possible due to the soul’s intentional state with respect to the affection of the organ. When human beings sleep, the sense organs continue to be impressed by the species from sense objects; however, this impression, without the attention of the soul, does not give rise to any act of perception. The sensory soul turns upon itself and sees itself as being similar (reflectendo aciei uidet se talem) to the species of the sensible object. When the soul turns its eye upon itself, the soul sees the sensible object through the image made by itself in and from itself. […]
The object is the necessary occasion and the causa sine qua non (otherwise there would be nothing to be perceived) but not the sufficient cause of perception (DSF 103; 123). The efficient cause per se of perception is the immaterial soul—the division into sensory faculties is instrumental to the process and in most of this part of the treatise Kilwardby talks of the operations of the sensory soul (which he also calls the ‘incorporeal sensitive spirit’) as a unified entity. spiritus sensitivus thing. The image in the soul is not the same as the one in the sense organ.” (Silva, 2013)
extends “SENSITIVE SOUL is intentionally attentive to object“; includes “SENSE organ is passively impressed by the sensible species of the object
SENSITIVE SOULSENSITIVE SOUL is intentionally attentive to object
Sensory memory(Sensory memory) retains images: “Kilwardby argues that the power of memory is responsible for receiving the images of objects of knowledge by natural assimilation, for preserving the images of sensible objects, and for making them available for the powers of imagination” (Silva, 2016)includes “(Common sense) percepts likenesses of sensible species and apprehends the present object
Imagination(Imagination) creates images when object is not presentincludes “(Sensory memory) retains images
Intellectual memory(Intellectual memory) retains images: “Kilwardby argues that the power of memory is responsible for receiving the images of objects of knowledge by natural assimilation, for preserving the images of sensible objects, and for making them available for […] intellect” (Silva, 2016)includes “(Imagination) creates images when object is not present
IntellectIntellect abstracts universals as the common part of the multitude of images: “The universal is reached by the intellect considering that which is common (the ratio uniuersalis or ratio commune) to the multitude of images (or likenesses or phantasms or species) of sensible things (corporalia) retained by memory, without the particular circumstances of the images. […]
Scientific knowledge is certain and necessary because it is about what always is (De ortu scientiarum 47, 437–38). There is no science of individual sensible things existing here and now (hic et nunc), but only of universals. However, there is a continuity between the knowledge of images of particular objects in imagination and universals abstracted from them (the cognition of the former is directed to the cognition of the latter).” (Silva, 2013)
includes “(Intellectual memory) retains imagest
WillWill initiates action


  • Silva, José Filipe, “Robert Kilwardby“, The Stanford Encyclopedia of Philosophy (Winter 2016 Edition), Edward N. Zalta (ed.)
  • Silva, José Filipe, “Robert Kilwardby on the Theory of the Soul and Epistemology”, A Companion to the Philosophy of Robert Kilwardby, Christopher Henrik Lagerlund and Paul Thom (ed), Brill, 2013
  • J.F. Silva & J. Toivanen, “The Active Nature of the Soul,” Vivarium 48 (2010): 245–278.

First published: 4/2/2021