The Dead Ear: A Language Model’s Inherited Accent Is an Archive, Not an Author

Pope rhymed tea with obey; Shakespeare rhymed prove with love. Both pairs were sounds before they were conventions, and a model that learned rhyme from five centuries of verse learned it in accents nobody speaks. This paper asks whether those accents still write. Six documented sound changes generate 997 dead pairs inside a 1,532-pair item set, crossed against a spelling confound so that a model reading the page and a model reading inherited sound give different answers. Dead pairs are attested in rhyme position 37.9 times as often as matched controls across 2,816 dated public-domain poems, validating the set independently of any model. Claude Opus 5 treats dead rhymes as rhyme-like at 40.0% against a 1.2% non-rhyme floor, and still at 26.7% on pairs the corpus never attests. It writes them at 0.6%, below the most modern half-century in the corpus. Given a reasoning budget it accepts 100% of them. The inheritance is a reference library, consulted accurately and kept out of the writing. Asked to perform 1700, Opus reaches 6.9%, an interval lying entirely above the densest half-century in five hundred years, while the smaller Sonnet 5 lands on 2.4% — and 1700 was 2.41%. Fluency at evoking a period outruns fidelity to it.