Externalism and identity

The main aim of this paper is to show that there is one version of super-venience of the mental on the physical which is entailed by token-token identity (I call this version change-supervenience); and to establish that of the other better known versions of supervenience in the literature (which I call difference-supervenience), none are so entailed. One consequence of this is that Burge's thought experiments while successful in refuting difference-supervenience cannot in themselves refute identity thesis. However, the introduction of change supervenience leads me to devise an analogous thought experiment against change-supervenience, thus refuting identity thesis as well.