The Concept of Mind is a 1949 book by philosopher Gilbert Ryle, in which the author argues that "mind" is "a philosophical illusion hailing chiefly from René Descartes and sustained by logical errors
Cover of the first edition
In philosophy of mind, the hard problem of consciousness is to explain how and why organisms have qualia, phenomenal consciousness, or subjective experience. It is contrasted with the "easy problems"
The Concept of Mind
…between the two poles of pontificating authority and easy-going chumminess," something Marcuse finds to be characteristic of philosophical behaviorism. Hard problem of consciousness Logical behaviorism…
David Chalmers on stage for an Alan Turing Year event at De La Salle University, Manila, 27 March 2012
The hard problem is often illustrated by appealing to the logical possibility of inverted visible spectra. If there is no logical contradiction in supposing that one's colour vision could be inverted, it follows that mechanistic explanations of visual processing do not determine facts about what it is like to see colours.