Justifying Conceptual Development Claims: response to van Haaften

This paper is a response to van Haaften's attempt to build ‘a natural bridge from “is” to “ought”’ and in doing so to provide a general account of how, in developmental theory, a claim that ‘a later stage in conceptual development is somehow better or more adequate than preceding ones’ can itself be justified. The account by van Haaften violates the ‘seems justified/is justified’ distinction and embroils him in a problematic form of relativism. This paper offers an alternative account of such claims in terms of stage‐independent criteria of adequacy.