The influential analysis of David Lewis suggests that a regularity holds as a matter of convention when it solves a problem of co-ordination in a group. This means that it is to the benefit of each member to conform to the regularity, providing the others do so. Any number of solutions to such a problem may exist. For example, it is to the advantage of each of us to drive on the same side of the road as others, but indifferent whether we all drive on the right or the left. One solution or another may emerge for a variety of reasons. It is notable that on this account conventions may arise naturally; they do not have to be the result of specific agreement. This frees the notion for use in thinking about such things as the origin of language or of political society. See also conventionalism.
Philosophy dictionary. Academic. 2011.