Edna Ullmann-Margalit

“... in so far as conformity to a co-ordination norm ensures the achievement of some co-ordination equilibrium, which for everyone involved in the corresponding co-ordination problem belongs of necessity to the group of preferred outcomes, it is rational for everyone to conform to it. Are we to conclude from this, however, that the social choice to which the co-ordination norm is instrumental is itself rational? My answer to this question is that although it is rational to conform to a prevailing co-ordination norm, the social choice resulting from it is not necessarily rational. [...] it may not be optimal, for some or for all involved. It can in principle be changed into a better one, only this involves an explicit process which is not always feasible. [...] The changing of an existing convention in favour of a 'better', more rational one, has to be explicit. It can be achieved through an explicit agreement of all concerned, or through a regulation (decree) issued and properly promulgated by some appropriately endowed authority. Where communication, or promulgation, is impossible, it is difficult to see how an existing convention (which is a co-ordination norm) might be changed. It is of some interest to note that whereas an 'act of convening' is not necessary for a convention to form, it might be necessary for an existing convention to be exchanged for an alternative one.”
― Edna Ullmann-Margalit, The Emergence of Norms