Ghost buster: The reality of one’s own body

What are the epistemic bases of the knowledge of the reality of our own body? Proprioception plays a primordial role in body representation and more particularly at the level of body schema. Without proprioception people can feel amputated and the mislocalization of proprioceptive information through the remapping of the Penfield Homonculus induces illusions of phantom limbs, illusions that contradictory visual feedback cannot erase. However, it turns out that it is not as simple as that and that vision also intervenes in body knowledge: vision of one’s own body allows deafferented patients to move and phantom limbs to disappear. Finally, the existence of phantom limbs in aplasic patients as well as studies on neonates provide evidence of an innate component of body representation. Descartes applied his systematic doubt on the reality of his own body: nothing assured him that he had a body, that he was not dreaming or hallucinating its existence. More recently, Putnam (1981) has suggested that we could be disembodied brains in a vat and that the experience of our own body could be the result of electric impulses from a large computer. At the end of their reflections, Descartes and Putnam refuted skepticism and assumed that people do have bodies. I do not want to study how they reached this conclusion here, nor to address the metaphysical question of the reality of the body. Rather, the focus of this paper will be the epistemological question of the knowledge of body existence: how do I know that I have a hand rather than that I am amputated? The answer seems to be obvious, I can see my hand and I can feel it. But it is not always so