 In “New Work For a Theory of Universals”, Lewis notes another restriction that is needed. If we measure the simplicity of some truths by the length of their statement in an arbitrarily chosen language, then any truth at all can be made simple. Let Fx be true if and only if x is in a world where every truth in this Encyclopedia is true. Then Everything is F is simply stateable in a language containing F, and is presumably strong. So Everything is F will be a law. But this kind of construction would clearly trivialise the theory of laws. Lewis’s solution is to say that we measure the simplicity of a claim by how easily stateable it is in a language where all predicates denote perfectly natural properties. He notes that this move requires that the natural properties are specified prior to specifying the laws, which means that we can’t reductively specify naturalness in terms of laws. (In any case, since Lewis holds that laws are contingent (1986a: 91) but which properties are natural is not contingent (1986a: 60n), this approach would not be open to Lewis.)