Prior Trustworthy 100-Year Digital Object articles describe a method for preserving digitally represented information. TDO representation and packaging makes any digital content reliably meaningful to consumers, no matter how distant these are in time, in space, and in social affiliation from their information sources. The current article provides part of an argument justifying the TDO proposal as sound and, in a certain sense, optimal. Specifically, it focuses on digital document authenticity and evidence with which a consumer can prudently decide whether to trust the content. Such justifications are necessarily epistemological. Arguing the issues must start by conveying as unambiguously as possible what we mean by words like ‘authenticity’ and ‘evidence’ and by distinctions such as that between ‘objective’ and ‘subjective’. The arguments apply Wittgenstein’s teaching to pictorial models of digital and conventional communication. The analysis leads us to identify an ethical imperative for digital preservation, and to suggest that the TDO method defines a quality standard against which any method of digital preservation should be judged.