The mind-body problem

In short: The mind-body problem asks how mind and body are connected: how can thoughts, feelings and consciousness be linked to the physical processes in the brain?

In more detail: Since antiquity, and especially since René Descartes in the 17th century, very different answers have been given. To this day the question has not been finally settled in philosophy or neuroscience.

In detail

• The basic question: A pain feels a certain way from the inside, while measurable nerve activity takes place in the brain; the dispute is whether these are two sides of the same thing or two different things.
• Substance dualism: Descartes distinguished a thinking substance (mind) from an extended substance (matter) and then had to explain how the two act on each other.
• The interaction problem: Since Descartes, critics have asked how a non-material mind could move a material body without breaking physical laws.
• Materialism and physicalism: These positions assume that everything mental ultimately comes down to physical processes, such as processes in the brain.
• Identity theory: It claims that a particular mental state is simply identical with a particular brain state.
• Functionalism: Here a mental state is defined by its role, that is by what it causes and what triggers it, regardless of the material in which it is realised.
• The hard problem of consciousness: The philosopher David Chalmers called it the hard problem to explain why physical processes are accompanied by subjective experience at all.
• Relevance today: The question matters in brain research, in medicine and in debates about whether machines could ever be conscious (rationalismus-und-empirismus, chinesisches-zimmer-gedankenexperiment, freier-wille-und-determinismus).