Individuation by agreement and disagreement

It is common to explain agreement and disagreement in terms of relations among mental states. The main purpose of the present discussion is to present an alternative way of thinking about the relationship between mental states and agreement and disagreement. The idea is to connect agreement and disagreement with the individuation of mental states. More specifically, for at least some mental states, standing in the same relations of agreement and disagreement is both necessary and sufficient for identity. This provides us with a framework for discussing issues related to agreement and disagreement. It is for instance well-known that de se beliefs raise questions about agreement and disagreement. The present framework allows us to discuss such beliefs while relying on assumptions that are interestingly different from the standard assumptions in the literature. While most of the discussion focuses on beliefs, there are other mental states, such as desires, that can seemingly also stand in relations of agreement and disagreement. This raises questions about how far the framework can be extended.