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.
