The nature of the mind and the relation of the mind to the body and to the physical world have been vexing problems for modern philosophy. French mathematician, philosopher, and physiologist René Descartes formulated the most influential version of dualism, the view that the mind and the body are two different types of entities. As a physiologist, Descartes understood that the human body could be understood as a mechanism. He believed that the mind, being rational, could not be reduced to mechanistic physics. Therefore, he concluded that human beings consist of two distinct parts, a mind that is pure thought and a body that is extended in physical space. This raised questions of how pure thought could cause bodily action and how sensations in the flesh could be communicated to the spiritual half.
Many materialists have argued that the mind-body problem created by Descartes’s dualism is a result of a mistaken adherence to the concept of a nonphysical soul. Scientists have been able to identify areas of the brain responsible for speech, memory, and even personality traits. If the mind is seen as nothing but the electrochemical operations of the brain, though, this can create further problems. Thoughts, images, and emotions are not just influences on human behavior; they are also experiences in awareness, and it is difficult to find awareness in discharges of neurotransmitters.
In the preface to one of his later books, Consciousness Explained (1991), Daniel C. Dennett remarked that he had been hooked on the mind-body problem ever since his first year in college, when he read Descartes. Dennett’s first book, Content and Consciousness (1969), was an attempt to develop a unified, comprehensive theory of the mind as a product of mechanistic, physical forces. The seventeen essays in Brainstorms were efforts to revise and extend this theory by addressing different aspects of the nature of the mind.