 Among the most familiar objections to this proposal is that there is no principled distinction between when a creature is learning and when it is done learning. Instances in which a creature entertains the hypothesis that “X” means X, instances in which the creature entertains the hypothesis that “X” means Y, instances in which the creature straightforwardly uses “X” to mean X, and instances in which the creature straightforwardly uses “X” to mean Y are thoroughly intermingled. The problem is perhaps more clearly illustrated with tokens of natural language, where children will use words struggling through correct and incorrect uses of a word before (perhaps) finally settling on a correct usage. There seems to be no principled way to specify if learning has stopped or whether there is instead “lifelong learning”. This is among the objections to be found in Fodor (1984).