A scholar discovered an unlabeled nineteenth-century recording of someone reciting a poem written by Walt Whitman. During the nineteenth century, recordings of poetry were not made for wide commercial sale. Rather, they were made either as rare private souvenirs of the voices of famous poets or else as publicity stunts, in which actors recorded poems that were familiar to the public. Since the Whitman poem in the recording was never even published, it is likely that the voice in the recording is actually Whitman' s. The argument proceeds by ['explaining the historical context of an incident in order to demonstrate that each of the two possible scenarios involving that incident is as likely as the other', 'distinguishing a phenomenon into two subtypes and then for a particular case eliminating one of those subtypes', 'showing that two apparently mutually exclusive alternatives are actually compatible with one another', 'offering a general principle and then demonstrating that the general principle is violated in a particular case']