Paul M. Churchland

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Article abstract: An analytic philosopher and proponent of eliminative materialism, Churchland maintained that advances in the neurosciences and artificial intelligence are the key to understanding cognition. A leading defender of scientific realism, he held that scientific theories present a literally true account of the world, especially of the unobservable world.

Early Life

Paul Montgomery Churchland, a dual American/Canadian citizen, was born in Vancouver, Canada, in 1942. He studied at the University of British Columbia, Vancouver, from 1960 to 1964, and graduated with a B.A. (honors) in philosophy, physics, and mathematics. From 1964 to 1967, he studied at the University of Pittsburgh, one of the world’s leading centers for studies in the philosophy of science. He received his Ph.D. from this institution in the fields of philosophy of science and philosophy of mind. In 1966, Churchland served as an instructor in philosophy at the University of Pittsburgh at Greensburgh and then moved to the University of Toronto, where he served as a lecturer in philosophy from 1967 to 1969, moving in 1969 to the University of Manitoba, where he rose from assistant professor to full professor.

Life’s Work

In 1982-1983, Churchland was a member of the Institute for Advanced Study in Princeton, New Jersey. In 1984, Churchland became a professor of philosophy at the University of California, San Diego. At that university, he served as department chair from 1986 to 1990 and was a member of the Cognitive Science Faculty, a member of the Institute for Neural Computation, and a member of the Science Studies faculty.

An important component of Churchland’s philosophy deals with the metaphysical mind-body problem, posed in its sharpest form by the French philosopher René Descartes, called the father of modern philosophy. Descartes asked: What do human beings have that material objects do not have that allows human beings to cognize, to learn languages, and to learn mathematics? He argues that human beings must have an immaterial, nonspatial mind over and above a material, spatially located brain that inanimate objects and lower life forms do not have. Descartes called this mind “mental substance,” the essence of which is thinking. This substance is to be contrasted with material substance, the essence of which is extension, the occupying of space. These two substances are the basis of Descartes’s metaphysical dualism. (For Descartes, there was also a third substance, divine substance, or God.) These substances have necessary existence and need nothing else for their existence. For Descartes, the separation of material substance from mental substance meant that science (which deals with material substance) would never have to come into conflict with religion (which deals with mental substance, or spirit, or soul). Nevertheless, a problem immediately arose as to the nature of the causal interaction between an immaterial, nonspatial mind and a material, spatial body. Descartes held that the interaction occurred in the pineal gland, but this answer simply postpones the problem rather than solving it. To this day, no generally received answer to this mind-body problem has been provided by philosophers, psychologists, or neuroscientists.

Although few modern scholars hold Descartes’s theory of substance dualism, there are, nevertheless, many varieties of contemporary dualism. Popular dualism, for example, holds that the mind is a spiritual substance yet fully possessed of spatial properties in intimate contact with the brain. Other dualistic theories claim that the mind is a property of the material brain. For example, epiphenomenalism holds that the mind is an emergent property of the brain that is not causal to other events, whereas interactionist property dualism holds that mental states emerge from the brain but can causally interact with the...

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brain and other parts of the material body. A sophisticated form of dualism centers on the notion ofsupervenience. Things of kind A supervene on things of kind B when the presence or absence of things of kind A is completely determined by the presence or absence of things of kind B. It is sometimes argued that the mental supervenes on the physical but that mental categories are not identical with nor reducible to any physical categories.

In contrast to these dualistic theories, reductive materialism, more often called “the identity theory,” holds that mental states are physical states of the brain. An even more popular materialist theory is functionalism, which holds that the defining feature of any type of mental state is the set of causal relations it bears to environmental effects on the body, other types of mental states, and bodily behavior. So pain, for example, typically results from bodily injury, causes annoyance and distress, and causes wincing, blanching, and the nursing of the injured area. Any state that plays exactly the same functional role is pain, according to functionalism. A third type of materialism is eliminative materialism, which holds that the theory of mental states is impoverished, not simply incorrect. There are no mental states, only brain states.

Eliminative materialism is the philosophical theory held by Churchland. He argues that the position is supported by advances in the neurosciences. Neuroscientists routinely produce color-coded images of the actual patterns of activity in the brain when people read, attend to different features of visual stimuli, encode and retrieve memories, and perform other cognitive tasks. Other neuroscientists produce very detailed maps of the primate cortex that distinguish dozens of specialized processing areas. Much support for eliminative materialism is also found in studies of cases of brain damage, degeneration, and disequilibrium. For example, lesions to the connections between the secondary visual cortex and the secondary auditory cortex of the left hemisphere may result in the inability to identify perceived colors, while lesions to the secondary auditory cortex of the left hemisphere results in the more drastic effect of total and permanent loss of speech comprehension, while bilateral damage to the hippocampus results in the inability to retain new memories.

Nevertheless, eliminative materialists such as Churchland must still account for the phenomenon of introspection and the “qualitative feel” of people’s alleged mental states. The eliminative materialist must account for the differences people claim to perceive, for example, in pain, their understanding of a mathematical problem, and their believing or knowing a fact. A strong case can be made that these latter phenomena are best explained under some dualist theory of mind-brain.

The argument from introspection in favor of a dualism of mind-brain is a serious problem for Churchland. He responds to it by invoking a robust scientific realism, which is, basically, the position that scientific theories provide a literally true account of the world. Moreover, Churchland claims that, if scientific theories are successful at explaining and predicting phenomena, then there is good reason to believe that the entities that the theories postulate really exist, even if they are not directly perceivable through the senses. For example, the standard model theory of matter claims that electrons, protons, quarks, and other subatomic entities exist even if people do not directly perceive them with their senses. As Churchland argues, when one experiences a warm summer day as 70 degrees Fahrenheit, what one is experiencing is the mean kinetic energy of the air molecules, which is about 6.2 x 10 -21 joules, whether one realizes it or not, for heat is the mean kinetic energy of molecules. If one does not perceive it that way, one can learn to do so.

This realism is important for Churchland, for it allows him to formulate a response to the argument from introspection, the strongest argument against the eliminative materialism that Churchland embraces. Churchland argues that, with suitable training and knowledge, one can eventually introspect one’s brain states directly. This claim undercuts the dualist position that one introspects one’s mental states that exist over and above the brain. However, this leads to one of the most controversial of Churchland’s theses, for he claims that eventually one can directly introspect such brain states as spiking frequencies in specific neural pathways and dopamine levels in the limbic system, based on a realist account of current and successful neurophysiological theories.

To support this controversial claim, Churchland presents the case of the musical prodigy who, at a very early age, can distinguish between sound pitches. Very soon, with more training and study, the young person can distinguish between different instruments of the orchestra. As the prodigy matures and becomes a talented young conductor, he or she can distinguish when instruments in an orchestra are playing in tune and when they are not. Churchland then draws an analogy with the introspection of brain states. He claims that people will have to learn the conceptual framework of a matured neuroscience if they are to introspect brain states directly and that they will have to practice its noninferential application. Eventually they will reach the stage analogous to that of the mature conductor who can now experience phenomena that were impossible to experience at an earlier stage of development. Churchland thinks that the amount of self-apprehension gained by direct introspection of brain states is more than worth the effort of training and study. Several problems arise with regard to Churchland’s argument. The most obvious problem concerns the precision of his argument by analogy.

As an eliminative materialist, Churchland is quick to use parallel distributive processing (PDP) from artificial intelligence research as a model of cognitive processes. Such digital computers function solely as symbol manipulators, and it is unclear whether any symbol manipulator—whether a computer or a human being—can ever possess intentionality, the state of having meanings that point to, or are about, features of the world. Typically, intentionality is said to be “the mark of the mental.” The philosopher John R. Searle argues that mere symbol manipulators cannot have semantics or meanings and thus cannot have intentionality. Thus, according to the computational model of conscious intelligence held by Churchland, a brain that simply manipulates symbols cannot account for people having meanings that are about the world. However, as many philosophers hold, a dualist theory of mind-brain can. Meanings (or propositions) are just the objects of mental states.

Searle uses his famous Chinese room argument (of which there are several versions) to argue his case. Suppose Searle himself is a central processing unit (CPU) of a digital computer and understands no Chinese at all. If Searle is given rules of syntax, he can string together Chinese characters and output them in such a way that a person fluent in Chinese could read the resulting string of symbols, understand them, and respond. However, he, Searle, cannot respond even though as a CPU he gives the appearance of knowing what the symbols mean. Searle argues that the meaning of the symbols has intentionality, and hence the Chinese speaker can understand and respond appropriately to the output sentence in a way that Searle as a mere symbol manipulator cannot. Therefore, brains or computers that can only manipulate symbols according to a program cannot have intentionality. Intentionality can be had only by objects that have a conscious mind, such as the Chinese speaker. Searle claims that his argument holds independently of technological advances in computer design. This argument presented a serious challenge to Churchland’s eliminative materialism and the associated view that the material brain is merely a neurocomputer.

Churchland countered Searle’s argument with his own “luminous room” argument. Churchland asked the reader to imagine a small, closed-off room that is completely dark. The occupant of this room is the scientist James Clerk Maxwell, who claims that light is nothing other than electromagnetic waves. Maxwell shakes a bar magnet that produces such waves. An outside critic points out that the room is completely dark, so light cannot possibly be electromagnetic waves. Churchland says that all Maxwell needs to do is claim that the room is indeed lit, albeit at a grade too poor to be detected. All that is needed for visible light is that the electromagnetic waves be speeded up in order to produce visible light. The same is true for Searle’s argument, claims Churchland. All that is needed is that the syntax of a language be sufficiently complex in order for people to detect the meaning and thus the intentionality of symbol manipulation. Churchland’s argument, however, again suffers from problems arising from analogy. Scientists, for example, do not say there is light unless it is visible, even if moving electromagnetic waves are present. More important, it is not clear that speeded-up electromagnetic waves giving rise to visible light is analogous to increased syntactical complexity of language giving rise to meaning.

Additional Reading

Bechtel, William. “What Should a Connectionist Philosophy of Science Look Like?” In The Churchlands and Their Critics, edited by Robert N. McCauley. Oxford, England: Blackwell Scientific Publications, 1996. The author is also a major figure in the field of philosophy and cognitive science. He holds that traditional philosophy of science has been little concerned with the psychology of science, and that the general sentential approach of traditional philosophy of science is ineffective. Bechtel nevertheless questions Paul M. Churchland’s claim that theories and explanations are best understood in terms of representations in the heads of scientists.

Clark, Andy. “Dealing in Futures: Folk Psychology and the Role of Representations in Cognitive Science.” In The Churchlands and Their Critics, edited by Robert N. McCauley. Oxford, England: Blackwell Scientific Publications, 1996. This article is written by another major leader in the field of philosophy and cognitive science. Clark agrees with the Churchlands that connectionist models can contribute very valuable, new resources for understanding human cognition. However, he forcefully rejects Churchland’s claim that this outcome impugns folk psychology.

Flanagan, Owen. “The Moral Network.” In The Churchlands and Their Critics, edited by Robert N. McCauley. Oxford, England: Blackwell Scientific Publications, 1996. Flanagan defends Churchland’s moral network theory. He examines the potential of this theory for making sense of moral learning, knowledge, practices, and standards. He applauds the way the theory illuminates the biological, psychological, and social forces shaping the moral lives of human beings, while the normative component of the theory can assess right and wrong, good and bad.

Fodor, Jerry, and Ernie Lepore. “Paul Churchland and Stated Space Semantics” and “Reply to Churchland.” In The Churchlands and Their Critics, edited by Robert N. McCauley. Oxford, England: Blackwell Scientific Publications, 1996. In both of these articles, the authors argue that Churchland’s state space version of a network account of semantics is wanting. They argue that Churchland has remained committed to two positions that are incompatible.

Lycan, William G. “Paul Churchland’s PDP Approach to Explanation.” In The Churchlands and Their Critics, edited by Robert N. McCauley. Oxford, England: Blackwell Scientific Publications, 1996. Lycan discusses Paul Churchland’s prototype activation account of explanatory understanding. Lycan argues that if explanation concerns either quasi-logical relations between sentences or the natural relations between the affairs those sentences represent, then Churchland’s objections to the traditional deductive-nomological model of scientific explanation are ineffective.

McCauley, Robert N. “Explanatory Pluralism and the Co-evolution of Theories in Science.” In The Churchlands and Their Critics, edited by Robert N. McCauley. Oxford, England: Blackwell Scientific Publications, 1996. The author is a leader in the field of the philosophy of cognitive science. He discusses Churchland’s account of intertheoretic relations in science and the implications for a scientific psychology as opposed to folk psychology. He argues that the earlier continuum model advanced by Churchland and his wife, Patricia Churchland, is vastly oversimplified, leading to unwarranted expectations about the elimination of psychology in favor of advanced neuroscience.