The ‘Brain-in-a-vat’ thought experiment (Putnam, 1982) tells us the meaning of having a body. If a brain surgeon removes someone’s brain from the body, place it in a vat full of life-sustaining liquid and connect it to the computer providing electrical impulses through wires that are identical to those a brain normally receives…then what happens?
Of course it is important whether the brain will have the ordinary conscious states or not. But even if so, the brain-in-a-vat (removed from the body) still includes bodily dimensions that cannot be eradicated. According to Legrand (2010), there are four kinds of such dimensions.
[Legrand, D. (2010). Myself with No Body? Body, Bodily-Consciousness and Self-consciousness. In S. Gallagher and D. Schmicking (eds.) Handbook of Phenomenology and Cognitive Science. Springer.]
1. EXPERIENTIAL Dimension: If the surgery does not alter the conscious experience, this means that the subject would experience the body equally after the surgery. The body is eliminated but the bodily-consciousness is not.
2. ANATOMICAL Dimension: The vat is full of necessary nutriments, which allows the brain’s life-regulation. The life-sustaining liquid substitutes the roles of physiological functions and anatomical structure of the body.
3. SENSORIMOTOR Dimension: The computer connected to the brain would create perceptual and kinesthetic experiences. That would substitute the sensorimotor dimension of the real body.
4. NEURONAL Dimension: Corporeal representation in the brain (body representation, body map, body image, etc.) would be still present in the brain after the surgery.
Thus, the thought experiment totally contradicts the experimenter’s original intention of disembodiment. The brain-in-a-vat as a ‘disembodied brain’ paradoxically affirms the being of the various bodily dimensions.