The relation between two systems of attitude ascription that capture all the empirically significant aspects of an agent's thought and speech may be analogous to that between two systems of magnitude ascription that are equivalent relative to a transformation of scale. If so, just as an object's weighing eight pounds doesn't relate that object to the number 8 (for a different but equally good scale would use a different number), similarly an agent's believing that P needn't relate her to P (for a different but equally adequate interpretive scheme could use a different proposition). In either case the only reality picked out by any system of ascription is what is common to all equivalent rivals. By emphasizing some contrasts between decision theory and belief-desire psychology, it is argued here that if attitude ascription is appropriately analogous to measurement, then not only is being related to a proposition an artifact of the system of representation chosen, but so are belief and desire.