 The I-language concept brushes aside certain phenomena of interest to the Externalists, who hold that the forms of actually attested expressions (sentences, phrases, syllables, and systems of such units) are of interest for linguistics. For example, computational linguistics (work on speech recognition, machine translation, and natural language interfaces to databases) must rely on a conception of language as public and extensional; so must any work on the utterances of young children, or the effects of word frequency on vowel reduction, or misunderstandings caused by road sign wordings. At the very least, it might be said on behalf of this strain of Externalism (along the lines of Soames 1984) that linguistics will need careful work on languages as intersubjectively accessible systems before hypotheses about the I-language that purportedly produces them can be investigated.