Gary Hatfield

The quantitative experimental scientific psychology that became prominent by the turn of the twentieth century grew from three main areas of intellectual inquiry. First and most directly, it arose out of the traditional psychology of the philosophy curriculum, as expressed in theories of mind and cognition. Second, it adopted the attitudes of the new natural philosophy of the scientific revolution, attitudes of empirically driven causal analysis and exact observation and experimentation. Third, it drew upon investigations of the senses. Natural philosophical disciplines such as optics and acoustics treated the functioning of the senses. Optics, in particular, had from antiquity comprised a complete theory of vision, combining the physics, physiology, psychology, metaphysics, and epistemology of vision, using mathematical techniques where feasible. Within medicine, sensory physiology examined anatomy, physiology, and pathology. Philosophical psychology had long examined the senses as mental capacities connected with cognition and knowledge, and such discussions also heeded the new attitudes of natural philosophy. This chapter first examines the early relations of psychology to biology and characterizes various eighteenth-century loci of psychological thought. It then pursues nineteenth-century developments in Germany and Britain that culminate in the “new” psychology of the 1860s and 1870s.

This chapter examines the relations between psychology and neuroscience. There is a strong philosophical intuition that direct study of the brain can and will constrain the development of psychological theory. When this intuition is tested against case studies from the psychology of perception and memory, it turns out that psychology has led the way toward knowledge of neurophysiology. The chapter presents an abstract argument to show that psychology can and must lead the way in neuroscientific study of mental function. The opposing intuition is based on mainly weak arguments about the fundamentality or objectivity of physics or physiology in relation to psychology. The chapter argues that psychological phenomena are methodologically prior to neurophysiological concepts and descriptions, that psychology provides the functional descriptions that guide the behavioral brain sciences, that psychological concepts are not reducible, but that neurophysiological data and concepts are nonetheless evidentially and explanatorily relevant for psychology.

It seems intuitively obvious that metameric matching of color samples entails a loss of information, for spectrophotometrically diverse materials appear the same. This intuition implicitly relies on a conception of the function of color vision and on a related conception of how color samples should be individuated. It assumes that the function of color vision is to distinguish among spectral energy distributions, and that color samples should be individuated by their physical properties. I challenge these assumptions by articulating a different conception of the function of color vision, according to which color vision serves to partition object surfaces into discrimination classes.

Some experiments in perceptual psychology measure perceivers’ phenomenal experiences of objects versus their cognitive assessments of object properties. Analyzing such experiments, this article responds to Pizlo’s claim that much work on shape constancy before 1985 confused problems of shape ambiguity with problems of shape constancy. Pizlo fails to grasp the logic of experimental designs directed toward phenomenal aspects of shape constancy. In the domain of size perception, Granrud’s studies of size constancy in children and adults distinguish phenomenal from cognitive factors

This introductory chapter surveys some basic findings on primate evolution and the evolution of mind; examines socially transmitted traditions in relation to the concept of culture; recounts the sources of evidence regarding the evolution of mind and culture; charts the history of evolutionary approaches to mind and behavior since Darwin; reviews several prominent theoretical syntheses concerning the evolution of the human mind and behavior; and, along the way, introduces the specific questions examined in the individual chapters.

Shape and slant judgments of rotated or frontoparallel ellipses were elicited from three groups of 10 subjects. A masking stimulus was introduced to control processing time. Backward masking trials were presented with interstimulus intervals of 0, 25, and 50 msec, Reduction of processing time altered shape judgments in the direction of projective shape and slant judgments in the direction of frontoparallelness. This finding is consistent with the shape-slant invariance hypothesis. In order to study the effects of processing load, one group of subjects was given prior knowledge of the kind of judgment to be made on each trial, one group had no prior knowledge, and a third group made both judgments on each trial. The effects of the processing load manipulation were interpreted in terms of the role of attention in perceptual encoding. Consistent with previous findings, allocation of attention did not affect perceptual encoding.

In the Aristotelian curriculum, De anima or the study of the soul fell under the rubric of physics. This area of study covered the vital (“vegetative”), sensitive, and rational powers of the soul. Descartes’ substance dualism restricted reason or intellect, and conscious sensation, to human minds. Having denied mind to nonhuman animals, Descartes was required to explain all animal behavior using material mechanisms possessing only the properties of size, shape, position, and motion. Within the framework of certainty provided by the metaphysical foundations of his physics, he posited such mechanisms in accordance with appropriately lessened standards of certainty. As Cartesianism (or the Cartesian revolution) spread, adherents offered survey textbooks or treatises of physics to replace the corresponding Aristotelian curriculum. These books typically discussed the role of experience in physics and the appropriate standard of certainty. A comprehensive Cartesian natural philosophy needed to mechanize the offices of the Aristotelian sensitive soul, including sense perception, memory, and cognitive and appetitive responses to the environment. Descartes’ Treatise on Man (1664) offered an initial explanatory program. This chapter examines the role of experience in the natural philosophy and mechanistic psychology of Descartes’ English follower Antoine Le Grand. He offered detailed accounts of the sensory and motor mechanisms shared by human and nonhuman animals (for which he claimed “physical certainty”). These frame his Cartesian psychology.

The chapter begins with an initial survey of ups and downs of contextualist history of philosophy during the twentieth century in Britain and America, which finds that historically serious history of philosophy has been on the rise. It then considers ways in which the study of past philosophy has been used and is used in philosophy, and makes a case for the philosophical value and necessity of a contextually oriented approach. It examines some uses of past texts and of history that reveal limits to noncontextual history, including Strawson's Kant, Rorty's grand diagnosis of the Western tradition, and Friedman on Kant's philosophy of mathematics. It then considers ways in which the history of philosophy may become philosophically deeper by becoming more historical, and instances in which history of philosophy of various stripes has or may deliver a philosophical payoff. Along the way, it urges historians of philosophy to attend not only to individual philosophers and their problems and projects, but also to the larger shape of the history of philosophy and its narrative themes.

Descartes boldly claimed: "I think, therefore I am." But one might well ask: Why do we think? How? When and why did our human ancestors develop language and culture? In other words, what makes the human mind human? _Evolution of Mind, Brain, and Culture_ offers a comprehensive and scientific investigation of these perennial questions. Fourteen essays bring together the work of archaeologists, cultural and physical anthropologists, psychologists, philosophers, geneticists, a neuroscientist, and an environmental scientist to explore the evolution of the human mind, the brain, and the human capacity for culture. The volume represents and critically engages major theoretical approaches, including Donald's stage theory, Mithen's cathedral model, Tomasello's joint intentionality, and Boyd and Richerson's modeling of the evolution of culture in relation to climate change. The volume contains chapters by: Peter Carruthers; Thierry Chaminade; Philip Chase; Merlin Donald; Peter Gardenfors; Gary Hatfield; Jody Hey; Steven Mithen; April Nowell; Peter Richerson and Robert Boyd; Theodore Schurr; Robert Seyfarth and Dorothy Cheney; Kim Sterelny; and Felix Warneken. ISBN 978-1-934536-49-0

The theory of knowledge in early twentieth-century Anglo American philosophy was oriented toward phenomenally described cognition. There was a healthy respect for the mind-body problem, which meant that phenomena in both the mental and physical domains were taken seriously. Bertrand Russell's developing position on sense-data and momentary particulars drew upon, and ultimately became like, the neutral monism of Ernst Mach and William James. Due to a more recent behaviorist and physicalist inspired "fear of the mental", this development has been down-played in historical work on early analytic philosophy. Such neglect assumes that the "linguistic turn" is a proper and permanent effect of twentieth-century philosophy, an assumption that distorts early analytic historiography, and begs a substantive philosophical question about thought and cognition.

It is difficult to evaluate the role of activity - of force or of that which has causal efficacy - in Descartes’ natural philosophy. On the one hand, Descartes claims to include in his natural philosophy only that which can be described geometrically, which amounts to matter (extended substance) in motion (where this motion is described kinematically).’ Yet on the other hand, rigorous adherence to a purely geometrical description of matter in motion would make it difficult to account for the interactions among the particles that constitute Descartes’ universe, since the notions of extension and kinematical motion do not in themselves imply any causal agency. There is, after all, no reason to expect that a particle whose single essence is extension, even if we suppose it to be moving, should impart motion to another particle, while conversely, there is no reason to expect a resting particle to hinder the motion of an impinging one. Descartes' hankering for an austere ontology of matter in motion is in danger of excluding causal agency (force, conceived dynmically) from matter. To the modern reader it may seem obvious that Descartes did not get himself into such a fix, since matter in motion so readily reminds us of kinetic energy or of some more primitive notion of force. Yet by no means is it obvious that Descartes attributed causal efficacy to matter in motion per se. Serious scholars have held opposite positions on this issue. Westfall, Gabbey, and others’ have argued that although on the metaphysical plane Descartes attempted to eliminate force from his mechanical universe, nonetheless ‘force is a real feature’ of his mechanical world. The thrust of this view is that Descartes conceived of force as ‘the capacity of a body in motion to act’, by means of impact, upon other bodies. An opposing interpretation, defended here, is that Descartes did in fact deny causal agency to moving matter per se, restricting agency to immaterial substances such as the human mind, angels, and God. The intention of this interpretation is not to de-emphasize the role of matter in motion in Descartes’ explanation of nature, but rather to stress the fact that Descartes did not conceive of this moving matter dynamically. Reprinted in Descartes, ed. by J. Cottingham, Oxford Readings in Philosophy (Oxford: Oxford University Press, 1998), 281–310.

The chapter examines some common assumptions regarding the shape of the history of theories of mind. It questions the conception that the Scientific Revolution resulted in placing the mind “outside of nature.” During the seventeenth century, the followers of Descartes routinely placed study of the mind, or, at least, mind–body interaction, within “physics” considered as a science of nature in general (and so including physics in the narrow sense, biology, and psychology). By the end of the eighteenth century, many authors treated the psychological and the physical as distinct areas of investigation (with points of contact, to be sure), both amenable to natural scientific study. Another assumption is that, prior to behaviorism, the notion of “the psychological” was equivalent to “the mental.” And yet, during the seventeenth century psychological phenomena were assigned to both sides of the mind–body divide: the Cartesians and their allies offered (nonmentalistic) mechanistic explanations for the sensory and behavioral capacities that human beings share with animals, while also holding that some aspects of mental life (including consciousness, free will, conceptual language, and general intelligence) require an immaterial mind. Finally, from the late eighteenth century onward, some have maintained that if mental states are reached only by introspection then they cannot be studied objectively. The chapter argues that the standard version of this objection misunderstands the nature of introspection, and it mounts a reply founded on Wundt’s methodological discussions and making reference to the perceptual investigations of the Gestalt psychologists.

Descartes understood the subject matter of physics (or natural philosophy) to encompass the whole of nature, including living things. It therefore comprised not only nonvital phenomena, including those we would now denominate as physical, chemical, minerological, magnetic, and atmospheric; it also extended to the world of plants and animals, including the human animal (with the exception of those aspects of the human mind that Descartes assigned to solely to thinking substance: pure intellect and will). Descartes wrote extensively on physiology and on the physiology and psychology of the senses. This chapter examines the notions of *physiology* and *psychology* in medical and natural philosophical works of Descartes' day; follows his efforts to bring physiology into his mechanistic idiom; considers the relation between physiology of the animal machine and psychological functions that yield functionally appropriate behavior; goes into his physiology and psychology of vision; and elaborates the tension in Descartes' works between his metaphysically supported micro-corpuscularism and his discussion of the animal machine as an organic unity comprising various functionally and teleologically characterized systems. The chapter draws on Descartes' works in both metaphysics and natural philosophy, including his Treatise on Man (originally published as L'Homme, 1664).

Visual space can be distinguished from physical space. The first is found in visual experience, while the second is defined independently of perception. Theorists have wondered about the relation between the two. Some investigators have concluded that visual space is non-Euclidean, and that it does not have a single metric structure. Here it is argued that visual space exhibits contraction in all three dimensions with increasing distance from the observer, that experienced features of this contraction are not the same as would be the experience of a perspective projection onto a fronto-parallel plane, and that such contraction is consistent with size constancy. These properties of visual space are different from those that would be predicted if spatial perception resulted from the successful solution of the inverse problem. They are consistent with the notion that optical constraints have been internalized. More generally, they are also consistent with the notion that visual spatial structures bear a resemblance relation to physical spatial structures. This notion supports a type of representational relation that is distinct from mere causal correspondence. The reticence of some philosophers and psychologists to discuss the structure of phenomenal space is diagnosed in terms of the simple materialism and the functionalism of the 1970s and 1980s

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.

Behaviorism was a peculiarly American phenomenon. As a school of psychology it was founded by John B. Watson (1878-1958) and grew into the neobehaviorisms of the 1920s, 30s and 40s. Philosophers were involved from the start, prefiguring the movement and endeavoring to define or redefine its tenets. Behaviorism expressed the naturalistic bent in American thought, which came in response to the prevailing philosophical idealism and was inspired by developments in natural science itself. There were several versions of naturalism in American philosophy, and also several behaviorisms. Most behaviorists paid homage to Darwinian functionalism; all forswore introspection and made learned changes in behavior the primary subject matter and explanatory domain of psychology. They differed in their descriptions of behavior, modes of explanation, and attitudes toward mentalistic concepts. Watson was a strict materialist who wanted to eliminate all mentalistic talk from psychology. Edward Chace Tolman (1886-1959) regarded mind as a biological function of the organism. He permitted mentalistic terms such as 'purpose' in behavioral description, and posited intervening processes that included 'representations' of the environment, while requiring such processes be studied only as expressed in behavior. Clark L. Hull (1884-1952) developed a hypothetical-deductive version of behaviorism, akin to Tolman's functionalism in positing intervening variables but without his cognitivist constructs. B. F. Skinner (1904-90) rejected intervening variables and developed his own account of the behavior of the whole organism, based on the laws of operant conditioning. The naturalism in American philosophy of the early twentieth century showed respect for the natural sciences, especially biology and psychology. John Dewey (1896, 1911), George Santayana (1905, 1920), and F. J. E. Woodbridge (1909, 1913) expressed this attitude. It animated the neorealism of E. B. Holt and Ralph Barton Perry, who gave special attention to psychology, and the evolutionary naturalism and critical realism of Roy Wood Sellars. This naturalism differed from Watson's in regarding mind as part of nature from a Darwinian and functionalist perspective, and treating behavior as the product of the mental functioning. It fed Tolman's version of behaviorism. It was not materialistic or physical-reductionist. Only later, with Quine and logical empiricism, was behaviorism seen as essentially physicalistic.

This paper develops an appearance view of perception (focusing on vision). When we see an object, we see it by having it appear some way to us. We see the object, not the appearance; but we see the object via the appearance. The appearance is subjectively conditioned: aspects of it depend on attributes of the subject. We mentally have the appearance and can reflect on it as an appearance. But in the primary instance, of veridical perception, it is the object that we focus on and experience. I contrast this view with naive realism (sometimes called disjunctivism) (Brewer, Campbell, Noe) and with intentionalist or representationalist views, which I call the physical content view (Dretske, Tye, Crane, Hill, Burge). I agree with these views in rejecting sense-data intermediaries and in affirming direct perception, but I argue that direct perception occurs via appearances, making mine a critical direct realism. The other views attempt to explain the spatial content of perception (shape, size, distance) entirely through the physical properties of objects and their physical relation to the perceiver (viewing position). I argue instead that there are ineliminably subjective aspects of normal spatial perception, which are systematically manifested as a lack of full phenomenal constancy. This systematic underconstancy can’t be accounted for at all by a consistent naive realism; for the physical content view, it requires that most of our ordinary perception is classified as illusory, violating the spirit of that view. Accepting phenomenal underconstancy as pervasive, I suggest that our ability to perceive the mind-independent properties of objects depends on developed conceptual abilities. In the final section, I compare my appearance view with the adverbialism of Chisholm and the critical direct realism of Roy Wood Sellars.

Descartes was both metaphysician and natural philosopher. He used his metaphysics to ground portions of his physics. However, as should be a commonplace but is not, he did not think he could spin all of his physics out of his metaphysics a priori, and in fact he both emphasized the need for appeals to experience in his methodological remarks on philosophizing about nature and constantly appealed to experience in describing his own philosophy of nature. During the 1630s, he offered empirical support for the basic principles of his natural philosophy, while also promising to provide a metaphysical justification. He offered the metaphysical justification in the Meditations and Principles. and claimed absolute certainty for it. At the same time, he recognized that the particular postulated mechanisms of his natural philosophy did not reach that standard of certainty. These mechanisms were supported by empirical testing or confirming of causes through observed effects

This paper argues for the reality of qualia as aspects of phenomenal experience. The argument focuses on color vision and develops a dispositionalist, subjectivist account of what it is for an object to be colored. I consider objections to dispositionalism on epistemological, metaphysical, and 'ordinary' grounds. I distinguish my representative realism from sense-data theories and from recent 'representational' or 'intentional' theories, and I argue that there is no good reason to adopt a physicalist stance that denies the reality of qualia as phenomenally available intentional contents in Brentano's original sense of 'intentionality'.

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.

Mandelbaum adopted a middle course between physicalistic scientific realism and phenomenalistic "ordinary language" direct realism. He affirmed the relevance of scientific knowledge for epistemology, but did not attempt to reduce the content of perception to physical properties. Rather, he developed a critical direct realism, according to which we see bodies by means of having phenomenal experience. This phenomenal experience was not, however, to be equated with the sense-data of the usual representative realism. Rather, it was a perception of material objects by means of their qualities. In this way, he agreed with the phenomenological position of the Gestalt psychologist Wolfgang Koehler, who rejected the view that sense-data by themselves could provide an epistemic basis for knowledge claims. Koehler's position, too, may be described as a critical realism. As would Mandelbaum, he sought to give proper due to the phenomenal while also affirming its basis in a physical world of objects and brain processes. In its insistence on the reality and scientific respectability of the phenomenal, the critical realism of Mandelbaum and Koehler is distinct from the contemporaneous physicalism of Place and Smart.

In philosophical writings from Descartes’ time, the topic of attention attracted notice but not systematic treatment. In Descartes’s own writings, attention was not given the kind of extended analysis that he devoted to the theory of the senses, or the passions, or to the intellect and will. Nonetheless, phenomena of attention arose in relation to these other topics and were discussed in terms of mental operations and, where appropriate, relations to bodily organs. Although not producing a systematic account, Descartes frequently noted attentional phenomena and creatively imagined intricate relations between sensory attention and brain processes. Descartes's observations of attentional phenomena show remarkable breadth, including cases of active mental control of attention and cases in which attention is drawn involuntarily to a novel event (first section). Descartes did not merely observe attentional phenomena; he also offered a framework for understanding them (second section). Part of this framework related attention to the activity of the will. Part also came from his conception of mind-body interaction. He assigned a significant functional role to brain processes in explaining mental phenomena, including aspects of attention. He sometimes moves beyond the usual notions of unidirectional activity or passivity in the process of interaction. Rather, mind and brain are mutually constraining. Mental and physiological processes form a functional unity, in which brain processes contribute to the mental functioning of attention (final section). Furthermore, Descartes was willing to speak of “attention” in the mindless machine portrayed in his Traité de l’homme. That work describes brain states that interact with mind to explain aspects of mental attention. But we must also suppose that these same brain states constitute attention as it occurs in non-human animals, which lack a mind. According to Descartes, although attention is, in the first instance, a mental phenomenon, it can also be ascribed to non-human animals that share brain mechanisms with human beings and the behavior of which can be described as attentively directed toward selected objects in the environment. Translated into French by Olivier Dubouclez.

There is a strong philosophical intuition that direct study of the brain can and will constrain the development of psychological theory. When this intuition is tested against case studies on the neurophysiology and psychology of perception and memory, it turns out that psychology has led the way toward knowledge of neurophysiology. An abstract argument is developed to show that psychology can and must lead the way in neuroscientific study of mental function. The opposing intuition is based on mainly weak arguments about the fundamentality or objectivity of physics or physiology in relation to psychology. -/- Philosophy of Science, Vol. 67, Supplement. Proceedings of the 1998 Biennial Meetings of the Philosophy of Science Association. Part II: Symposia Papers (Sep., 2000).

This chapter compares rationalist theories of sense perception to previously held theories of perception (especially of vision) and examines rationalist accounts of sensory qualities and sensory representation, of the role of the sense-based passions in guiding behavior, of the epistemological benefits and dangers of sense perception, and of mind–body relations. Each section begins with Descartes, the first major rationalist of the seventeenth century. The other major rationalists, Malebranche, Spinoza, and Leibniz, and also lesser known figures such as Pierre Regis, Jacques Rohault, and Antoine Le Grand, were well acquainted with Descartes' work. Indeed, the first three were each deeply influenced by Descartes in their early years before developing their own philosophical systems, and the latter three were all advocates of Descartes' philosophy (perhaps with slight revision). Each of the major rationalists, while sharing some positions in common, developed a distinctive metaphysics of perception and of the mind–body relation. Earlier sections chart these differences and a final section sums up common features and touches on the continuing significance of their views.

Recent Cartesian scholarship postulates two Descartes, separating Descartes into a scientist and a metaphysician. The purpose varies, but one has been to show that the metaphysical Descartes, of the Meditations, is less genuine than the scientific Descartes. Accordingly, discussion of God and the soul, the evil demon, and the non-deceiving God were elements of rhetorical strategy to please theologians, not of serious philosophical argumentation. I agree in finding two Descartes, but the two I identify are not scientist and philosopher, but practitioner and methodologist of the mathematical sciences on the one hand, and metaphysician of a new, general science of nature on the other. This chapter examines the transition to the second Descartes, and especially the metaphysical turn. It proposes that although Descartes' doubt was methodological and he felt no serious threat from skepticism and absolute certainty was not his primary goal. Rather, the doubt was used to reform the intellect, or to teach the use of the pure intellect (and to obtain certainty in that domain). Further, Descartes' metaphysics was primarily in the service of his natural philosophy (where in the main he did not claim absolute certainty). He did not talk about God and the soul in order to fool the theologians. His discussion of the relation between God and human reason was part of a metaphysical strategy in which, through his doctrine on the eternal truths, he separated knowledge of the first principles of natural philosophy (gained by the natural light) from theological cognition (through the light of grace), thereby seeking to render his metaphysics distinct from the proper domain of theology.