<P> The "ghost in the machine" is British philosopher Gilbert Ryle's description of René Descartes' mind - body dualism . The phrase was introduced in Ryle's book The Concept of Mind (1949) to highlight the view of dualist systems like Descartes' where mental activity carries on in parallel to physical action, but where their means of interaction are unknown or, at best, speculative . </P> <P> Gilbert Ryle (1900--76) was a philosopher who lectured at Oxford and made important contributions to the philosophy of mind and to "ordinary language philosophy". His most important writings include Philosophical Arguments (1945), The Concept of Mind (1949), Dilemmas (1954), Plato's Progress (1966), and On Thinking (1979). </P>

What is meant by the phrase ghost in the machine