A standard approach in historically minded disciplines to documents and other artefacts that have become suspect is to concentrate on their dissimilarities with known genuine artefacts. While such an approach works reasonably well with relatively poor forgeries, more skilfully done counterfeits have tended to divide expert opinions, demanding protracted scholarly attention. As there has not been a widespread scholarly consensus on a constrained set of criteria for detecting forgeries, a pragmatic maximum for such dissimilarities—as there are potentially an infinite numbers of differences that can be enumerated between any two artefacts—has been impossible to set. Thus, rather than relying on a philosophically robust critical framework, scho...