The “brain in a vat” thought experiment is presented and refuted by appeal to the intuitiveness of what the author informally calls “the eye for an eye principle”, namely: Conscious mental states typically involved in sensory processes can conceivably successfully be brought about by direct stimulation of the brain, and in all such cases the utilized stimulus field will be in the relevant sense equivalent to the actual PNS or part of it thereof. In the second section, four classic problems (...) of Functionalism are given novel solutions based on the inclusion of peripheral nervous processes as constituents of mental states: The mad pain problem, the problem of pseudo-normal vision, the China-brain problem, and the triviality problem. (shrink)