Peter Alan Morton

A central aspect of the computational theory of vision developed by Marr and his coworkers is the use made of contingent regularities in the physical environment to explain how the visual system determines the shape and location of objects in the world on the basis of the spatial organization of the retinal image. Marr (1982) refers to these environmental regularities as “natural constraints” and “physical assumptions.” In this paper I am concerned with recent arguments concerning the implications of this feature of Marr’s theory for understanding psychological explanation. Burge (1986) claims that Marr’s use of natural constraints shows the theory to be nonindividualistic, in the sense that the individuation of psychological states depends essentially on the objects and conditions of the world external to the subject. While it does capture an important aspect of Marr’s theory, Burge’s account is misleadingly incomplete. To see this it is useful to compare the issue of individualism with the question whether the theory is compatible with methodological solipsism as a research strategy.

This book introduces students to the principal issues in the philosophy of mind by tracing the history of the subject from Plato and Aristotle through to the present day. Over forty primary-source readings are included. Extensive commentaries from the editors are provided to guide student readers through the arguments and jargon and to offer necessary historical context for the readings. The new third edition examines some of the most exciting recent developments in the field, including advances in theories about the mind’s relation to action and agency. Previous editions of this book, published under the title _A Historical Introduction to the Philosophy of Mind_, have been praised and widely taught for more than two decades.

This expanded and revised second edition of Morton's A Historical Introduction to the Philosophy of Mind combines primary readings with detailed commentary. The book has two aims: to present the philosophy of mind from a historical perspective so that the theories in the field are seen to emerge in the process of solving problems with earlier theories; and to give the students access to the original source material together with commentaries that explain the technical terms and jargon, outline the argumentative structure, and place the texts in their historical context. The second edition adds several new chapters covering recent issues in the field, and revises earlier chapters to improve the readings and update the commentaries. The readings and commentaries begin with Plato and Aristotle, and then explain the implications of the scientific revolution for philosophy of mind. The philosophies of the early modern period include Cartesian dualism, Hobbesian materialism, and Berkeley’s idealism. The second part of the book surveys the developments in philosophy of mind in the twentieth century, including behaviourism, identity theory, and functionalism. In the third part, the readings and commentary survey contemporary problems if philosophy of mind, including artificial intelligence, consciousness, intentional semantics, and mental causation

This paper considers the implications of David Marr's computational theory of vision for the issues of individualism and methodological solipsism. A recent argument that the theory is nonindividualistic is shown to be similar to Gibson's arguments for "direct perception." The paper argues that a complete analysis of Marr's theory must take into account Marr's rejection of Gibson's approach, and that such an analysis shows Marr's theory to be consistent with methodological solipsism as a research strategy.

The thesis examines the philosophical implications of the computational theory of early vision developed by Marr. According to Marr, early visual processes consist of sequences of "modular" computational mechanisms. These processes rely on functional relations between rates of change in stimulus magnitudes which result from certain contingent, global properties--natural constraints--of the physical world. ;Marr argues that explanations of early vision must have three distinct levels of description: computational, algorithmic and physical. In Chapter 1 I defend the explanatory significance of this distinction in levels. In fulfilling its role in describing the dependence of visual processes on natural constraints, the computational level forms an autonomous level of description in the sense that it is unaffected by the computational steps at the other levels. ;In Chapter 2 I discuss the implications of natural constraints for the issues of individualism and methodological solipsism. I conclude that Mart's theory is nonindividualistic in the sense that visual content does not supervene on neural properties. However, this merely reflects the fact that different computational theories may be selected for the same system. Importantly, Marr's theory does not violate methodological solipsism since interpretations within theories must supervene on neural properties. ;In Chapter 3 I argue from the results of Chapters 1 and 2 that psychological explanation does not reduce to neurophysiology. This conclusion does not follow from the functionalist argument against physicalism, which is based on an incorrect account of computational theories. Rather the conclusion reflects the explanatory incompleteness of neurophysiological theories given the autonomous role of the computational level. ;In Chapter 4 I look in detail at the arguments for a "language of thought" as they apply to early vision. I distinguish two versions of the language of thought hypothesis, one weaker than the other. I conclude that the stronger version, which claims that a cognitive system is "program-using", is false of early vision because of the role of natural constraints. The weaker claim that cognitive processes employ symbolic transformations is true of the computational-level theory of early vision, but there is insufficient evidence to establish the claim at the algorithmic level

A Historical Introduction to the Philosophy of Mind is designed both to provide a selection of core readings on the subject and to make those readings accessible by providing commentaries to guide the reader through initially intimidating material. Each commentary explains technical concepts and provides background on obscure arguments as they arise, setting them in the historical and intellectual milieu from which they emerged. The readings concentrate on providing the student with a solid grounding in the theories of representative figures of the major philosophical movements, from Plato and Aristotle to important recent figures such as Fodor and Dennett. A glossary of key terms is also included