 Supposing representations are structured, then, what kind of structure do they have? Fodor notes that productivity and systematicity are features not just of thought but also of language, and concludes that representational structure must be linguistic. He endorses the idea of an innate, species-wide language of thought (as discussed briefly in §1.1 above); others tie the structure more closely to the thinker’s own natural (learned) language (Harman 1973; Field 1978; Carruthers 1996). However, still others assert that the representational structure underwriting belief isn’t language-like at all.