silicon chip replacement thought experiment:
A thought experiment proposed to support the notion of causal functionalism in Pylyshyn (1980)

To begin the thought experiment, imagine that you are the subject of some mental event--perhaps you are experiencing an intense pain. Now imagine that one of your neurons is replaced by a silicon chip prosthesis that has the exact same input/output profile as the neuron it replaces. At the core of this thought experiment is the presumption that such a replacement would be unnoticeable to you or to anyone observing your behavior. Presumably, you would continue to experience pain even though the physical realization of those mental events includes a silicon chip where an organic neuron used to be. Now imagine that, one by one, the rest of your neurons are swapped for silicon prostheses. Presumably there would be no change in your mental life even though your brain, which was once made of lipid and protein neurons, is now entirely composed of silicon neuronoids. The physical feature of your brain that has remained constant and in virtue of which you instantiate the same mental properties, is not the stuff of which it is made, but instead the causal relations that each part of the brain bears to the other. (The earliest mention of chip replacement thought experiments, as far as I know, is Pylyshyn (1980). For further discussion, see also Chalmers (1996),and Tye (1995).)
Pete Mandik