Gilbert Ryle (1900–1976) was a representative of the generation of British ordinary language philosophers influenced by Wittgenstein and is principally known for his critique of Cartesian dualism, for which he coined the phrase "the ghost in the machine". A capable linguist, he was recruited to intelligence work during World War II, after which he became Wayneflete Professor of Metaphysical Philosophy at Oxford, and published his principal work, "The Concept of Mind" in 1949. He was president of the Aristotelian Society from 1945 to 1946.

The Concept of Mind is a critique of the notion that the mind is distinct from the body, and it is a rejection of the theory that mental states are separable from physical states. According to Ryle, the classical theory of mind, as represented by Cartesian rationalism, asserts that there is a basic distinction between mind and matter. However, the classical theory makes a basic "category-mistake," because it attempts to analyze the relation between "mind" and "body" as if they were terms of the same logical category. This confusion of logical categories may be seen in other theories of the relation between mind and matter. For example, the idealist theory of mind makes a basic category-mistake by attempting to reduce physical reality to the same status as mental reality, while the materialist theory of mind makes a basic category-mistake by attempting to reduce mental reality to the same status as physical reality.

According to Ryle, mental processes are merely intelligent acts. There are no mental processes that are distinct from intelligent acts. The operations of the mind are not merely represented by intelligent acts, they are the same as those intelligent acts. Thus, acts of learning, remembering, imagining, knowing, or willing are not merely clues to hidden mental processes or to complex sequences of intellectual operations, they are the way in which those mental processes or intellectual operations are defined. Logical propositions are not merely clues to modes of reasoning, they are those modes of reasoning. Ryle rejects Descartes’ theory of the relation between mind and body, on the grounds that it approaches the investigation of mental processes as if they could be isolated from physical processes. In order to demonstrate how this theory may be misleading, he explains that knowing how to perform an act skillfully may not only be a matter of being able to reason practically but may also be a matter of being able to put practical reasoning into action. Practical actions may not necessarily be produced by highly theoretical reasoning or by complex sequences of intellectual operations. The meaning of actions may not be explained by making inferences about hidden mental processes, but it may be explained by examining the rules that govern those actions. The rationalist theory that the will is a faculty within the mind and that volitions are mental processes which the human body transforms into physical acts is therefore a misconception. This theory mistakenly assumes that mental acts are distinct from physical acts and that there is a mental world which is distinct from the physical world. This theory of the separability of mind and body is described by Ryle as "the dogma of the ghost in the machine". He explains that there is no hidden entity called "the mind" inside a mechanical apparatus called "the body." The workings of the mind are not an independent mechanism which governs the workings of the body. The workings of the mind are not distinct from the actions of the body and may be better conceptualized as a way of explaining the actions of the body.

Cartesian theory holds that mental acts determine physical acts and that volitional acts of the body must be caused by volitional acts of the mind. This theory is "the myth of the ghost in the machine". Ryle criticizes the theory that the mind is a place where mental images are apprehended, perceived, or remembered. Sensations, thoughts, and feelings do not belong to a mental world which is distinct from the physical world. Knowledge, memory, imagination, and other abilities or dispositions do not reside "within" the mind as if the mind were a space in which these dispositions could be placed or located. Furthermore, dispositions are not the same as behavioral actions, but actions may be explained by dispositions. Dispositions are neither visible nor hidden, because they are not in the same logical category as behavioral actions. Dispositions are not mental processes or intellectual acts, they are propensities which explain various modes of behavior. Perceptions, thoughts, emotions, and feelings may be understood as observable behaviors which have various modes of production. (extract, source: © review written by Alex Scott, click here to view the relevant webpage)