What ethics can learn from experimental economics -- If anything

Relying on the specific example of ultimatum bargaining experiments this paper explores the possible role of empirical knowledge of behavioural "norm(ative) facts" within the search for (W)RE -- (Wide) Reflective Equilibria on normative issues. Assuming that "pro-social" behaviour "reveals" moral orientations, it is argued that these "norm-facts" can and should be used along with stated preferences in justificatory arguments of normative ethics and economics of the "means to given ends" variety. At the same time behavioural norm-facts are so heterogeneous that any hopes to reach an inter-personally agreed (W)RE in matters moral seem futile.