Descartes’ mind-body dualism and his quest for objective knowledge can appear de-humanizing. My aim in this paper is to re-humanize Descartes. When we take a closer look at what Descartes actually says about human beings, it casts his entire thought in a much different light.

Two stories have dominated the historiography of early modern philosophy: one in which a seventeenth century Age of Reason spawned the Enlightenment, and another in which a skeptical crisis cast a shadow over subsequent philosophy, resulting in ever narrower "limits to knowledge." I combine certain elements common to both into a third narrative, one that begins by taking seriously seventeenth-century conceptions of the topics and methods central to the rise of a "new" philosophy. In this revisionist story, differing approaches to (...) the central subject matter of early modern metaphysics--knowledge of substances through their essences and causal powers--arise as a result of disagreements about the powers of the human cognitive faculties. Methodological writings are seen as attempts to direct readers in the proper use of their cognitive faculties. The early modern rejection of the Aristotelian theory of cognition ranks equally in importance with rejection of Aristotelian doctrines about nature. Skepticism is more often than not a tool to be used in teaching the reader the proper use of the cognitive faculties, or indeed in convincing the reader of the existence or inexistence of certain cognitive faculties or powers. Instead of early modern "epistemology" or "theory of knowledge," one speaks, with seventeenth century writers, of theories of the cognitive faculties and their implications for the possibility of human knowledge. The early modern rejection of Aristotelian logic can then be seen as reflecting a negative assessment about the fit between syllogistic reasoning and logic as an art of reasoning or thinking which refines the use of the cognitive faculties. -/- Central to this new historiography is the story of the relation between the intellect and senses as cognitive faculties or powers. The development of philosophy from Descartes to Kant can be portrayed as a series of claims about the power of the intellect to know the essences of things, with resulting consequences for ontology and the foundations of natural philosophy. I illustrate this revised narrative by comparing three conceptions of the intellect in three philosophical settings, provided by several late scholastic Aristotelians, Descartes, and Locke. I have two aims: first, to exhibit the central role played by the conception of intellect or understanding in these authors, and, second, to locate their discussions of the cognitive faculties in relation to recent understandings of psychology, epistemology, logic, mind, and their relations. Early modern writings do not easily fit into the modern categories of epistemology and psychology; more generally, the early modern concern with the workings of mind does not coincide with recent conceptions of naturalism. These findings can help us to see problems with our current categories. (shrink)

This chapter considers philosophical problems concerning non-human (and sometimes human) animals, including their metaphysical, physical, and moral status, their origin, what makes them alive, their functional organization, and the basis of their sensitive and cognitive capacities. I proceed by assuming what most of Descartes’s followers and interpreters have held: that Descartes proposed that animals lack sentience, feeling, and genuinely cognitive representations of things. (Some scholars interpret Descartes differently, denying that he excluded sentience, feeling, and representation from animals, and I consider (...) the evidence for these interpretations as well.) Given that Descartes denied any sort of soul to animals, his other philosophical commitments entailed that he must explain the vital and sensitive powers of non-human animals through purely material causes. Indeed, he welcomed this task, for he was engaged in the larger project of providing purely mechanistic explanations for all natural phenomena of the material world. Animal bodies form functional unities that are adapted to environmental circumstances. In his new physics, Descartes sought to discover or hypothesize material mechanisms that would explain the physiological and behavioral capacities of animals, including how they maintain themselves by seeking food and drink, reproduce themselves, and modify their behavior to fit current circumstances. Metaphysically, his new perspective raised the problem of accounting for the functional unity of the animal body considered as a purely material construction, devoid of an active, organizing power such as the sensitive soul. Descartes’s project becomes even more challenging if we ask whence come such mechanisms that are capable of performing the functions of living things. Officially, Descartes endorsed the accepted theological orthodoxy, that God designed and created the bodily mechanisms of humans and animals. However, in his natural philosophy he set himself the task of explaining the origin of animals as part of the natural development of the universe out of an original chaotic soup of material particles. Within this naturalistic perspective, he must explain how, through purely material processes, the functionally organized bodies of living things (plants and animals) could be produced from non-living matter. Without a designing creator, how do animal bodies arise that are capable of digesting food, growing, reproducing, and performing the behaviors needed to preserve life and health? (shrink)

This article seeks the origin, in the theories of Ibn al-Haytham (Alhazen), Descartes, and Berkeley, of two-stage theories of spatial perception, which hold that visual perception involves both an immediate representation of the proximal stimulus in a two-dimensional ‘‘sensory core’’ and also a subsequent perception of the three dimensional world. The works of Ibn al-Haytham, Descartes, and Berkeley already frame the major theoretical options that guided visual theory into the twentieth century. The field of visual perception was the first area (...) of what we now call psychology to apply mathematics, through geometrical models as used by Euclid, Ptolemy, Ibn al-Haytham, and Descartes (among others). The article shows that Kepler’s discovery of the retinal image, which revolutionized visual anatomy and entailed fundamental changes in visual physiology, did not alter the basic structure of theories of spatial vision. These changes in visual physiology are advanced especially in Descartes' Dioptrics and his L'Homme. Berkeley develops a radically empirist theory vision, according to which visual perception of depth is learned through associative processes that rely on the sense of touch. But Descartes and Berkeley share the assertion that there is a two-dimensional sensory core that is in principle available to consciousness. They also share the observation that we don't usually perceived this core, but find depth and distance to be phenomenally immediate, a point they struggle to accommodate theoretically. If our interpretation is correct, it was not a change in the theory of the psychology of vision that engendered the idea of a sensory core, but rather the introduction of the theory into a new metaphysical context. (shrink)

Historians of philosophy often credit Descartes, Locke, and other seventeenth-century authors with having introduced one of the most vexing problems into epistemology: the problem of mental representations. For these authors claimed that our knowledge of the external world is always mediated by mental representations, so that we have immediate access only to these representations, the ideas in our mind. As is well known, this “veil-of-ideas epistemology” gave rise to a number of skeptical questions. How can we be certain that our (...) ideas are accurate representations of the external world? And how can we be sure that there is an external world at all if we never have immediate access to it? In his highly original and provocative study, Robert Pasnau argues that these questions are not distinctively modern. They were already asked and thoroughly discussed by medieval authors: “much of what is often taken to be novel in the seventeenth and eighteenth centuries was already old news by the fourteenth”. According to Pasnau, it was Thomas Aquinas who introduced some form of representationalism into epistemology by developing the species-theory, and it was first Peter John Olivi and later William Ockham who attacked this theory, insisting that we always have immediate cognitive access to the external world. (shrink)

According to Kepler and Descartes, the geometry of the triangle formed by the two eyes when focused on a single point affords perception of the distance to that point. Kepler characterized the processes involved as associative learning. Descartes described the processes as a “ natural geometry.” Many interpreters have Descartes holding that perceivers calculate the distance to the focal point using angle-side-angle, calculations that are reduced to unnoticed mental habits in adult vision. This article offers a purely psychophysiological interpretation of (...) Descartes’s natural geometry. In his account of perceived limb position from the Treatise on Man, he envisioned a central brain state that controls ocular convergence and thereby co-varies with the distance from observer to object. A psychophysiological law relates the visual perception of distance to this brain state. Descartes also invokes more traditional theories of distance and size perception based on unnoticed judgments, yielding a hybrid account. (shrink)

This chapter contains section titled: Status of Animals Origins of Animals Life, Health, and Function Sense and Cognition Are Descartes's Animals Unfeeling Machines? Descartes's Legacy References and Further Reading.

Descartes's lack of clarity about the causal connections between brain states and mental states has led many commentators to conclude that he has no coherent account of body-mind relations in sensation, or that he was simply confused about the issue. In this paper I develop what I take to be a coherent account that was available to Descartes, and argue that there are both textual and systematic reasons to think that it was his considered view. The account has brain states (...) serving as occasions for the mind to produce in itself the sensations that it takes these brain states to signify. The relation between body and mind on this model is thus neither a standard efficient-causal relation, nor an occasionalist one, but rather a semantic-causal relation (i.e. a non-standard efficient causal relation that goes by way of natural signification). At the end of the paper I argue that the model does not undermine Descartes' commitment to the self-transparency of the mind. -/- . (shrink)

This chapter contains section titled: Institutions, Forms, Authorities Body as Substance Change and Causes Art and Nature References and Further Reading.

As the word “optics” was understood from antiquity into and beyond the early modern period, it did not mean simply the physics and geometry of light, but meant the “theory of vision” and included what we should now call physiological and psychological aspects. From antiquity, these aspects were subject to geometrical analysis. Accordingly, the geometry of visual experience has long been an object of investigation. This chapter examines accounts of size and distance perception in antiquity (Euclid and Ptolemy) and the (...) Middle Ages (Ibn al-Haytham), before turning to "natural geometry" in Kepler and Descartes. It finds a purely mechanical realization of natural geometry in Descartes (primarily in his L'Homme, 1664), in which he conceives states of the visual system as varying in accordance with distance, much as his geometrical compasses vary their spatial relations in accordance with geometrical proportions. This reading challenges the notion that a two-dimensional sensation (without three-dimensional phenomenality) was universally accepted prior to the nineteenth century by positing a direct psychophysiological account of the experience of distance in Descartes. It thereby challenges the interpretations of Descartes on natural geometry of George Berkeley, Nancy Maull, Margaret Wilson, Erwin Panofsky, and Jonathan Crary. (shrink)

In his recent study, Concepts, Fodor identifies five nonnegotiable constraints on any theory of concepts. These theses were all shared by the standard medieval theories of concepts. However, those theories were cognitivist, in contrast with Fodor’s: concepts are definitions, a form of natural knowledge. The medieval theories were formed under two influences, from Aristotle by way of Boethius, and from Augustine. The tension between them resulted in the Ockhamist notion of a natural language, concepts as signs. Thus conventional signs, spoken (...) and written, signify things in the world by the mediation of concepts which themselves form a language of thought, signifying those things naturally by their similarity. Indeed, later thinkers realised that everything signifies itself and what is like it naturally in a broad sense by means of the concept of its natural likeness. (shrink)

Descartes set for himself the ambitious program of accounting for the functions of the Aristotelian vegetative and sensitive souls without invoking souls or the faculties or powers of souls in his explanations. He rejects the notion that the soul is hylomorphically present in the organs of the body so as to carry out vital and sensory functions. Rather, the body’s organs operate in a purely mechanical fashion. That is what is involved in “mechanizing” these phenomena. The role of the soul (...) is restricted to properly mental functions: to the conscious aspects of sensations and other mental operations; to intellectual acts; and to acts of volition. In effect, soul becomes mind. In order to understand the extent of Descartes’ ambition, this chapter first considers more fully the functions attributed to the soul or to the vital faculties in the Aristotelian and Galenic traditions, and especially the functions of the sensitive soul or power. It draws attention to the cognitive aspects of these functions, beyond the mere operation of the external senses. Then it turns to Descartes’ mechanistic explanations for these cognitive functions. Finally, it situates Descartes’ new mechanistic psychology within the larger context of his novel anthropology, or theory of the human being. (shrink)

It is difficult now to imagine an intellectual landscape so thoroughly dominated by one figure as was that of the Schools by Aristotle. Except on certain well-known questions, the presumption was that Aristotle, suitably interpreted, was right. Nevertheless Aristotelianism was no frozen monolith. During the four centuries of its predominance, it continued to change, and admitted on all but fundamental points or those on which ecclesiastical authorities had pronounced, a great latitude—within, as in all such frameworks, the limits of its (...) thinkable. (shrink)