Article abstract: Dennett brought cognitive science and philosophy closer together by discussing the physical structures of the brain and artificial intelligence in his philosophy. Arguing convincingly against Cartesian dualism, Dennett became known as a staunch defender of a materialist philosophy of mind.

Early Life

Daniel Clement Dennett was born to an academic family. His father, Daniel Clement Dennett, Sr., was a historian and diplomat. His mother, Ruth Marjorie Leck Dennett, was a teacher and editor. An outstanding student, the young Dennett entered Harvard and graduated cum laude in 1963. While at Harvard, he married Susan Elizabeth Bell on June 8, 1962. Dennett has reported that he developed a fascination with the mind-body problem during his first year in college, when he read the work of the seventeenth century French philosopher René Descartes. Following his graduation, Dennett went to England to study philosophy at Oxford University, where he received a doctorate in philosophy in 1965. His chief mentor at Oxford was the philosopher Gilbert Ryle. Ryle and Dennett’s Harvard mentor, W. V. O. Quine, influenced Dennett’s style of writing as well as his materialist approach. Both of these older thinkers, Dennett later explained, always attempted to avoid jargon-laden writing and tried to write as though their readers would be nonphilosophers.

After he returned to the United States, Dennett took a position as assistant professor at the University of California, Irvine, in 1965 and remained there until 1971, having been promoted to the level of associate professor in 1970. He wrote his first book, Content and Consciousness, based on his doctoral dissertation, while in California. He moved to Tufts University in Medford, Massachusetts, in 1971. Although he would travel widely and serve as visiting professor at numerous universities, he continued to be on the faculty of Tufts throughout his career.

Life’s Work

Content and Consciousness established many of the themes that would appear in Dennett’s writings. It was in this book that he developed the idea of intentional systems, physical systems that could best be understood by seeing them as rational decision makers. The idea of intentionality was derived from the work of nineteenth century psychologist and philosopher Franz Brentano, who drew a distinction between mental phenomena and physical phenomena. Brentano maintained that mental phenomena could not be reduced to physical and mechanical events because mental phenomena show intentionality; they are directed upon objects in intentions, goals, wishes, desires, and interests. Dennett believed that Brentano’s distinction was a useful one. Dennett, however, argued that it was possible to see intentionality as a consequence of relations among material parts and not as a characteristic of spirit or soul. His argument drew heavily on Darwinian evolution, another theme that would continually reappear in his work. Dennett paid a great deal of attention to brain mechanisms, a focus that caused some philosophers to question whether his work should really be classified as philosophy.

In 1975, Tufts University promoted Dennett from associate professor to full professor in recognition of his many contributions to philosophy journals and of his growing professional reputation. The following year, he became head of the philosophy department at Tufts.

While serving in this position, he published a book of essays, Brainstorms: Philosophical Essays on Mind and Psychology. These essays extended and revised the theory of the mind Dennett had put forth in his first book. They discussed the nature of intentional systems, implications of Dennett’s philosophy for psychology, the nature of mental phenomena, and questions of morality and personhood.

Philosopher Douglas R. Hofstadter collaborated with Dennett in editing the volume The Mind’s I: Fantasies and Reflections on Self and Soul (1981). This was an unusual book for professional philosophers. It was a wide-ranging anthology of stories, fantasies, and speculative essays about the nature of the self and of consciousness, designed to stimulate imaginations and provoke questions, rather than to answer philosophical questions.

Dennett’s interest in exploring the relationship between the freedom of decision making and scientific concepts of causality led to his fourth book, Elbow Room: The Varieties of Free Will Worth Wanting. In this book, he reexamined the old philosophical question of whether human beings have free will. Most materialist thinkers would argue that thinking, as a product of physical determinants, cannot be free. Dennett, however, maintained that the deliberations of people are critical points in the process of producing actions. Therefore, people can be seen as having free will, even though the universe operates in a deterministic manner. A member of the American Civil Liberties Union, Dennett saw the question of free will as a political one and not simply as a disinterested philosophical issue.

In 1985, Dennett received the title of Distinguished Arts and Sciences Professor, and he became director of the Center for Cognitive Studies. This center consisted primarily of Dennett and an administrative assistant, and its function was to provide the philosopher with time to research, think, and write. Through the late 1980’s and 1990’s, Dennett produced a succession of books that were best-sellers by the standards of academic philosophy. In The Intentional Stance, he explored further his idea of the intentional system. The best way to predict the behavior of an animal or an information-processing machine is to suppose that these have beliefs and desires. He argued that beliefs and other types of intentional phenomena in people and other animals are virtual properties of brains that are similar to software in computers.

The application of the intentional stance to humans led Dennett to his theory of consciousness, expressed in his best-known and most controversial book, Consciousness Explained. In this work, Dennett argued against seeing consciousness as a “Cartesian theater,” as a homunculus (Latin for “little person”) inside the head viewing mental events from a command center. Such an explanation would make it necessary to in turn explain the thinking of the homunculus in terms of another little person inside of it and could lead to an infinite regression. Drawing on evidence from research in neurology, Dennett proposed a “multiple drafts” theory of mental activity. Versions of events are created through electrochemical processes throughout the brain. Consciousness, Dennett maintained, is an illusion of short-term memory. Consciousness developed through the course of evolution to enable humans to communicate with themselves, giving them the power to make decisions by providing them with the appearance of a single, unified flow of events. One of Dennett’s most provocative claims was that qualia, the intrinsic qualities of things in our experience, are also just illusions.

Dennett’s use of thought experiments and imaginative examples to build his argument made Consciousness Explained an intriguing book. It offered a convincing case for seeing human thinking as different from the processes of computers only in complexity and perhaps design but not in type of activity. Dennett offered one of the best challenges to the Chinese room thought experiment of philosopher John R. Searle. Searle had claimed that one could put a person who had no knowledge of the Chinese language in a room with detailed rules on how to construct sentences from Chinese characters. The sentences would seem meaningful to those outside of the room, even though the individual creating them did not really understand them. Nonconscious computing systems differ from humans, Searle maintained, because humans actually do understand the content of their own communication. Dennett’s response was that conscious beings seem to themselves to be doing something mysterious and ineffable called “understanding,” but that this understanding is really only a way of assembling and regulating information.

Some of Dennett’s critics have complained that Consciousness Explained was really “consciousness explained away.” They have asserted that detailing how consciousness might come into existence is different from saying what it is. Saying that it is an “illusion” is simply giving it a label. This label may also be misleading because there are mental representations that do approximate events in the world and other mental representations that do not, and only the latter are illusions in the normal use of the world. Finally, some critics have accused Dennett of simply replacing one set of metaphors, such as the “Cartesian theater,” with another set of metaphors, such as “multiple drafts.”

Darwinian evolution occupied a key place in Dennett’s explanation of consciousness. His next book, Darwin’s Dangerous Idea: Evolution and the Meanings of Life, was a detailed philosophical examination of Darwinian ideas. He claimed that Darwinism is a “dangerous idea” because it affects every area of life. It is a “universal acid” that eats away all of our traditional assumptions and leaves only a radical materialism. Natural selection can explain all phenomena and there is nothing to be explained by conscious design.

Kinds of Minds: Toward an Understanding of Consciousness was based on a series of Dennett’s public lectures. In it, he looked at old questions about different types of minds: Can fish think? Do lizards feel pain? Do developing fetuses have mental lives? He argued that these questions are unanswerable because they are badly posed. They are asked without knowing how fish or lizards or fetuses function in an intentional manner and without being clear about just what kinds of intentional behavior should be defined as conscious, given the lack of a clear demarcation between consciousness and “unconscious” intentional action. Brainchildren: Essays on Designing Minds followed similar themes. The last book was a collection of Dennett’s essays, book reviews, and other short writings from the previous two decades. These were divided into three sections, on philosophy of mind, artificial intelligence, and animal minds.

Influence

Over the course of his career, Dennett came to be recognized as one of the foremost and widely read authors in the philosophy of mind. His ability to make his arguments with witty anecdotes and vivid analogies and his avoidance of jargon gave his books an appeal beyond the narrow academic readership of most philosophy books. Within five years of its publication, Consciousness Explained had sold one hundred thousand copies, a huge sales figure for a serious work of philosophy. Darwin’s Dangerous Idea also reached a large number of readers and offered a convincing defense of strict Darwinian ideas in rebuttal of Darwinian revisionists and pseudo-scientific creationist theory.

Dennett’s works provided a way of seeing the mind that was materialistic without being behavioristic. In his early writings, the concept of intentional systems challenged the stimulus and response views of B. F. Skinner and other behaviorists who found no place for the mind in scientific theories. According to Duke University philosopher Owen Flanagan, Dennett’s idea of the intentional stance was a tremendous contribution to philosophy. At the same time, Dennett was deeply critical of those who wanted to rely on what he called “skyhooks,” ideas that seemed to hang from immaterial nothingness. He made special efforts to refute scientists who seemed to be looking for higher-order explanations that would give meaning to human life. Dennett’s materialistic insistence that consciousness was only an illusion made much of his work controversial. In particular, he engaged in a long and bitter debate with University of California philosopher John Searle, who maintained that there was a fundamental difference between human consciousness and the processes of computers.

Dennett played a central part in the development of the scientific study of consciousness and in the development of cognitive science. His willingness to draw on the work of psychologists, computer scientists, evolutionary biologists, and physicists helped to convince philosophers that these disciplines could contribute to philosophy. In turn, he demonstrated that when scientists attempted to understand their own work, they could be seen as doing philosophy.

Additional Reading

Churchland, Patricia S. Neurophilosophy: Toward a Unified Science of the Mind/Brain. Cambridge, Mass.: MIT Press, 1986. An influential introduction to philosophy of mind based on research into brain structures, this is written by one of Daniel C. Dennett’s philosophical critics.

Dahlbom, Bo, ed. Dennett and His Critics: Demystifying Mind. Oxford: Blackwell, 1993. This is a collection of eleven essays that criticize and defend Dennett’s ideas. It includes an essay by Dennett himself, “Back from the Drawing Board.” The editor’s introduction is a good summary of the controversies surrounding the philosopher’s concepts. Some of the pieces strongly oppose Dennett’s theories. Readers should see especially “Fillin in: Why Dennett is Wrong,” by Patricia S. Churchland and V. S. Ramachandran.

Dawkins, Richard. The Extended Phenotype: The Long Reach of the Gene. Rev. ed. Oxford: Oxford University Press, 1999. A readable introduction to Darwinian biology by a thinker who influenced Dennett. Dennett wrote the afterword for this book.

Dennett, Daniel C. “A Conversation with Daniel C. Dennett.” Interview by Tom Flynn and Tim Madigan. Free Inquiry 15, no. 4 (Fall, 1995): 19-21. In this interview, Dennett discusses his view that consciousness is an illusion that arises from short-term memory. He also argues that ideas about ethics do not necessarily depend on religion or on the existence of an immortal soul.

Dennett, Daniel C. “Daniel C. Dennett.” Interview by Robert K. J. Killheffer. Omni 17, no. 8 (Fall, 1995): 119-120. An interview with Dennett about Consciousness Explained, artificial intelligence, Darwinian theory, and other topics. The interview takes place at Dennett’s farmhouse and it gives a good sense of the man behind the theories.

Dennett, Daniel C. Interview by editors of the Journal of Cognitive Neuroscience. Journal of Cognitive Neuroscience 7, no. 3 (Summer, 1995): 408-414. The interview focuses on Dennett’s views on the connections between cognitive science and philosophy.

Searle, John. Intentionality: An Essay in the Philosophy of Mind. Cambridge, England: Cambridge University Press, 1983. A view of the intentional nature of the mind that offers an alternative to Dennett’s view, written by one of Dennett’s chief philosophical opponents.

Shafto, Michael G., ed. How We Know. New York: Harper and Row, 1985. A collection of essays about the nature of thinking, including an essay by Dennett and several that are relevant to Dennett’s thinking.