How are the mind and body harnessed together? In The Mind Incarnate, Lawrence Shapiro addresses this question by testing two widely accepted hypotheses, the multiple realizability thesis and the separability thesis. He argues that there is signficicant—though far from decisive—evidence against them.

While contemporary philosophers no longer view the mind as a supernatural entity—the famous "Ghost in the Machine" dogma that Gilbert Ryle ridiculed over fifty years ago—Shapiro argues that naturalistic approaches to understanding the mind retain their own naturalized varieties of ghosts. In particular, the multiple realizability thesis holds that the connection between human minds and human brains is in some sense accidental: the tie between mental properties and neural properties is not physically necessary. According to the separability thesis, the mind is a largely autonomous component residing in the body that contributes little to its functioning. Shapiro tests these hypotheses against two rivals, the mental constraint thesis and the embodied mind thesis. Collecting evidence from a variety of sources (e.g., neuroscience, evolutionary theory, and embodied cognition) he concludes that the multiple realizability thesis, accepted by most philosophers as a virtual truism, is much less obvious than commonly assumed, and that there is even stronger reason to give up the separability thesis. In contrast to views of mind that tempt us to see the mind as simply being resident in a brain or body, Shapiro view is a far more encompassing integration of mind, brain, and body than philosophers have supposed.