(b) A convention is a practice that solves a coordination problem within a community. The solution will bring mutual benefits but it will also be arbitrary. For example, the practice in North America of driving on the right is a convention in this sense: it is a mutually beneficial practice, but at least one other solution to the problem of avoiding head-on collisions is available: driving on the left. Natural languages (i.e., the use of languages by populations along the lines described in (a)) seem to be conventions in this simple sense. The existence of shared meanings within a community is clearly of mutual benefit, as evidenced, for example, by the use of English among English-speaking populations. It allows members of a population to learn one another’s thoughts about the world, for example. But there are many other solutions to the problem of finding out one another’s thoughts about the world, such as using Spanish or Japanese, so the choice is arbitrary.