Collective intention, social identity, and rational choice

In this paper I propose that what social psychologists refer to as social identity is a plausible empirical correlate on the part of the individual to what some philosophers and economists call collective intention. A discussion of an experiment yields the question what kind of mental state social identity might be and how it is related to the standard desire/belief conception. It is argued that social identity involves both a desire and a belief, and that one distinguishing feature of it is that it makes individual choice parametric.