In the philosophy of mind

Philosophy of mind

Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...

, the Brainstorm machine is a thought experiment

Thought experiment

A thought experiment or Gedankenexperiment considers some hypothesis, theory, or principle for the purpose of thinking through its consequences...

 described by Daniel Dennett

Daniel Dennett

Daniel Clement Dennett is an American philosopher, writer and cognitive scientist whose research centers on the philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the Co-director of...

, to show that it is not possible to intersubjectively compare any two individuals' personal experiences, or qualia

Qualia

Qualia , singular "quale" , from a Latin word meaning for "what sort" or "what kind," is a term used in philosophy to refer to subjective conscious experiences as 'raw feels'. Examples of qualia are the pain of a headache, the taste of wine, the experience of taking a recreational drug, or the...

, even with perfect technology. It is based on a device described in the film Brainstorm

Brainstorm (1983 film)

Brainstorm is a 1983 science fiction film directed by Douglas Trumbull and starring Christopher Walken and Natalie Wood...

, in which the visual experience of one individual is fed into the brain of another. According to Dennett in Quining Qualia: