Animal Implicatures: A Note on the Informativity Principle and Bayesianism

Several recent analyses of animal signals have proposed that when animals have the choice between a signal S and a more informative signal S+, S+ is preferred if it is true (= Informativity Principle). The principle is usually taken to apply both in production and in comprehension. A Gricean analysis currently lacks plausibility for lack of evidence for a theory of mind in the target species. But this doesn't mean that the animal Informativity Principle must be entirely taken as primitive. In fact, some uses of the principle in comprehension can be replaced with simple Bayesian reasoning. We explain in which cases this happens, and why the key data adduced for the Informativity Principle cannot be explained in this way because they involve production rather than comprehension. This suggests a new division of labor in which the animal Informativity Principle is primitive in production, but derived from Bayesian reasoning in comprehension.