Elena Baltuta (Humboldt University of Berlin) – Causation and Perception in Robert Kilwardby

Robert Kilwardby understands sense-perception as an active process performed by the sensitive soul when the body is affected by external objects. His account is based on the assumption that the world is hierarchically structured such that there can be no efficient upward causation. This means that in the specific case of sense-perception external objects cannot act as efficient causes. Such an account raises the following worry: How come sense-perception is about a particular external object, rather than about another, when there is no efficient causal connection between external objects and the sensitive soul? For instance, how come my soul perceives this oak tree, rather than that chestnut, if neither efficiently causes a change in my soul? In my talk I will address this worry and defend the thesis that according to Kilwardby external objects should be understood not as efficient, but as occasional causes for perception.

Daniel De Haan (University of Cambridge) – Perception, Practical Reason, and Prudence in Thomas Aquinas: The Function of the Vis Cogitativa

Many studies of Thomas Aquinas’s doctrines of practical reason, human action, and the cardinal virtues examine in detail the function the intellect, will, and passions. The function of the vis cogitativa or ratio particularis, however, is a neglected aspect of these doctrines in Aquinas. In this essay I demonstrate that appreciating the function of the ratio particularis is critical for understanding Aquinas’s integrated account of perception, practical reason, and prudence, and that omitting it renders his moral psychology incoherent. This is because the target of practical reason is singular actions. If, as most scholars suggest, practical reason comprises the intellect or universal reason alone, whose object is universals, and if prudence exclusively perfects this intellectual power, then the prudent practical reasoner is incapable of prudently apprehending and ordering their life towards singular actions. I argue that appreciating the function of the ratio particularis in Aquinas not only reveals that this line of argumentation is mistaken, but also provides a more coherent picture of Aquinas’s moral psychology.

Martin Klein (Humboldt University of Berlin) – John Buridan on the Singularity of Sense Perception

Against common interpretations of John Buridan’s theory of sense perception and singular cognition I’ll defend the following three claims: First, Buridan gives the same account for sense perception of human as well as non-human animals although the former have an immaterial and the latter a material soul. Second, Buridan does not think that sense perception could ever be a type of universal cognition even though he admits natural appetites, such as hunger and thirst, to be directed in a universal way. Third, sense perception is the paradigmatic case of singular cognition; however, the singularity of sense perception is not essentially due to the material nature of perceptive powers. Eventually, what distinguishes Buridan from other late medieval theories of sense perception is that he sharply differentiates the epistemological question of what it means to perceive something, namely to cognise it singularly, from the metaphysical question of how the intentional phenomenon of singular cognition is realised.

Andrew LaZella (University of Scranton) – Caesar in Bronze: Duns Scotus on the Sensation of Singulars

The story is often told that according to John Duns Scotus, our minds fail to register individual difference due to our embodied state. While this account is true, it remains partial. It does not explain why our senses do not sense accidents in their singularity. As will be shown in this paper, understanding this fact requires a more sustained treatment of how an object can move a cognitive power, and yet not move it according to the object’s mode of being. Just as Caesar cast in bronze does not take on the mode of being of its medium, so too our cognitive powers are assimilated to their agents, but not according to their modes of being. This non-identity belies a deeper metaphysical story such that the ratio agentis remains formally distinct from the ratio agendi. Thus, despite the immediacy of accidents to our sensory powers, we are not acquainted with their thisness due to the contingency of any individual’s identity.

Lukáš Lička (University of Ostrava) – Non sicut mus de foramine: Some 13th Century Approaches Towards the Extramissionist Explanation of Vision

The history of premodern optics and visual theory is often narrated as a clash between two competing paradigms – the intromission and the extramission – we see either by receiving an entity from the outside, or by means of something issuing from our eyes. Although it is sometimes believed that the intromissionist theory developed by Ibn al-Haytham (Alhacen) renders the extramissionist account obsolete, it is worth noting that Medieval Latin scholars still take the extramission quite seriously. The paper investigates three different approaches towards the extramission that were common among the 13th century Latin philosophers – refutation, syncretism, and reformulation. Four authors are especially examined – Albert the Great with his thorough refutation of different extramissionist theories; Roger Bacon and his syncretic tendencies to incorporate some extramissionist tenets into a broader intromissionist framework; the anonymous author of the Summa philosophiae (once ascribed to Robert Grosseteste) suggesting that the extramission postulate describes rather the dynamics of our visual power; and, finally, Peter Olivi with his full-fledged reformulation of the extramission and his understanding of the (visual) attention as a “virtual ray”. The paper thus argues that the extramission was not conceived as an antiquated theory by the 13th century thinkers, but it was carefully examined or even – in some cases – rethought and elaborated in an original way.

John Marenbon (University of Cambridge) – Sense-Perception and Immateriality in the 13th and 14th Centuries

I approach theories of perception in the context of my intermittent project about the overlapping but not coinciding medieval conceptions of immateriality and incorporeality (cf. http://www.phil.cam.ac.uk/events/thinking-and-self) . Although immateriality and incorporeality are most strikingly associated with intellectual cognition, thirteenth-century Latin thinkers held that, although sensible perception requires corporeal organs, it is to some extent not just a bodily process. What light do discussions of this in-between status of sensing through on the underlying notions of immateriality and incorporeality? I shall especially at how authors use the words ‘spiritual’, ‘spirit’ and ‘spirituality’ – terms central to many discussions of sense-perception, which can be used both by contrast with what is corporeal, but also for some special sorts of bodily things. The main authors considered will be Bacon, Kilwardby, Albert the Great and Aquinas.

André Martin (McGill University) – Peter John Olivi on Perception, Attention, and the Soul’s Orientation towards the Body

In this paper I examine Peter John Olivi’s account of perception. In particular, I examine Olivi’s notion of “attention” or “orientation” (aspectus) and I see how it fits into his general account of perception. As I put forward, Olivi uses the term “aspectus” in a variety of ways. Most often Olivi clearly uses the term “aspectus” to express something like our modern notion of selective attention. However, although less often, Olivi also notably uses the term “aspectus” in seemingly different contexts as, e.g., when he speaks of one cognitive faculty’s “aspectus” towards the lower faculty and its corporeal organs. As I argue, there is a potential tension between these uses as, e.g., Olivi insists that the aspectus of the soul in perception can directly tend outwards to external objects and yet this other “aspectus” seems to be only directly oriented towards the bodily senses and organs. I argue that in order to resolve this tension, and for other reasons, one should distinguish between conscious and non-conscious sorts of aspectūs in Olivi. As it turns out, I argue that with this distinction Olivi can retain parts of the prior “Aristotelian” accounts of perception which he famously criticizes without contrariety.

Mattia Mantovani (Humboldt University of Berlin) – Sensus spoliatus: The Perspectivists’ Distinction between Proper and Common Sensibles

In my presentation, I will investigate the theory of the sensibles of the leading vision theorists of the 13th century, the so-called perspectivists: Roger Bacon, Witelo, and John Pecham. I will argue that, by means of the aged distinction between proper and common sensibles, these thinkers intended to tell apart two stages of the visual process rather than explore the relation between different senses. They maintained that the proper visibles – light and color – are in fact the only visibles to be apprehended intuitively, whereas all the remaining visible features of an object demand some higher cognitive activity to be grasped, such as “discernment, inference and recognition”. In their views, light and color alone are indeed “apprehended only because they tinge the ultimum sentiens” – the brain, roughly speaking – after initially tinging the crystalline lens. In my presentation, I will show that the perspectivists construed the visual apparatus the way they did precisely to guarantee such a coloring of the sense organs relevant to the visual process. The theory of vision of the major experts in the field was thereby refuting Aquinas’ claim that the eye undergoes no material change in perceiving, but only a “spiritual” one. At the same time, I will argue that the perspectivists’ theory is not to be confused with William Crathorn’s, who extended the perspectivists’ claim about a physiological change of the sense-organs to all classes of sensibles.

Dominik Perler (Humboldt University of Berlin) – Rational Seeing: Thomas Aquinas on Human Perception

Aquinas holds that human beings perceive material objects in a rational way, since their sensory faculty is always under the guidance of the rational faculty. This paper intends to shed light on this fundamental thesis. First, it examines the metaphysical background, focusing on Aquinas’s claim that there is just one soul with interconnected faculties. Second, it looks at the interconnection in the case of perception, paying particular attention to the “vis cogitativa.” This special power is part of the sensory faculty, but it is always guided by the rational faculty and therefore produces perceptions that are conceptually structured: it enables human beings to see something as something. Third, the paper builds a bridge to recent theories of “transformative rationality.” Like the advocates of this theory, Aquinas claims that rationality is not simply added to perception, but rather something that is present in every act of human perception.

Saliha Shah (Indian Institute of Technology Delhi) – The Limits of Sense Perception: Avicenna on Internal Senses and Self-Awareness

The paper foregrounds the centrality of the event of sense perception in the thought of an important 11th century Islamic thinker Avicenna. While Avicenna’s fundamental epistemological concern is to demonstrate how knowledge takes place within the horizons opened up by perception, he has an elaborate account of the limits of sense perception. Avicenna seeks to identify those cognitive faculties of the sensitive soul that, subsequent to the initial reception of sense data by the external senses, co-operate upon the sensory inputs to produce a unified perceptual experience. He calls them “internal senses” (al-hawass al-batina). The paper discusses the role of the seven faculties that, for Avicenna, comprise the internal senses that supplement the perceptual powers of the external senses. The paper engages with Avicenna’s famous thought experiment known as “Flying Man” to a) account for the necessity of a unifying center of awareness that grounds the unity of soul’s operations, and b) explore the implications – philosophical and historical – of his difficult conclusion that awareness of the self is independent of all perception – external and internal.

José Filipe Silva (University of Helsinki) – The Chameleonic Mind: Medieval Augustinians on the Activity of Perception

In this talk, I will examine the so-called active model of perception of Augustinian origin, concentrating on how this model develops in selected late medieval thinkers. I will in particular consider whether and if so how the metaphors of the soul as a living wax and as a chameleon can be said to express the appropriate form of activity of the soul in perception and the nature of perceptual experience in this philosophical tradition.

Juhana Toivanen (University of Jyväskylä / University of Gothenburg) – ‘Perceiving as’ – A Theme and Medieval Variations

Sense perception primarily conveys information about the perceptual qualities of external objects: we see colours, hear sounds, taste flavours, and so forth. Yet, our experience of the external world contains several elements that cannot be reduced to these qualities. To name a few, external objects are perceived as three-dimensional bundles of properties, as useful or harmful for the percipient, as objects of desires, fears, and other emotions, and as conceptualised in various ways—in short, they are perceived as something.

It is well known that medieval philosophers recognised these phenomena, as they analysed various elements of perceptual experience, which are not (or cannot be) directly perceived by the external senses. In order to account for the psychological processes behind these elements, they argued that not only the external senses but several other cognitive powers of the soul contribute to perceptual experience. The leading idea in their approach was to divide complex psychological processes into sub-processes or functions, which can be attributed to various internal senses and the reason, and analysed separately.

My presentation focuses on medieval discussions concerning the psychological processes, which account for the complexity of our perceptual experience. I shall (1) specify the various types of phenomena, which medieval philosophers recognised and which can be put under the rubric ‘perceiving as’; (2) examine medieval psychological theories from the perspective of these processes; (3) suggest a theoretical model, which can be used to distinguish two different ways of conceptualising the psychological phenomenon of ‘perceiving as’; and (4) ask where the limit between conceptual and non-conceptual perception lies. Instead of concentrating on one or two medieval philosophers, I shall discuss relevant arguments from several thirteenth and fourteenth century authors.