 There is perhaps another sense in which the thinker “understands” Mentalese: her mental activity coheres with the meanings of Mentalese words. For example, her deductive reasoning coheres with the truth-tables expressed by Mentalese logical connectives. More generally, her mental activity is semantically coherent. To say that the thinker “understands” Mentalese in this sense is not to say that she represents Mentalese denotations. Nor is there any evident reason to suspect that explaining semantic coherence will ultimately require us to posit mental representation of Mentalese denotations. So there is no regress of understanding.