There are two main questions, or difficulties, that confront the examiner of an alleged forgery. The first of these is to determine how much and to what extent genuine writing will diverge from a certain type, and the second is how and to what extent will a more or less skillful forgery be likely to succeed and be likely to fail in embodying the essential characteristics of a genuine writing. Here we have the very hearth of the problem, for, at least in some measure, a forgery will be like the genuine writing, and there is also always bound to be some variation in the different examples of genuine writing by the same writer. Incorrect reasoning infers forgery from any variations or infers genuineness from any resemblance.
Albert S. Osborn, The Problem of Proof especially as exemplified in Disputed Documents Trials, Boyd, Albany 1946
Il problema è così posto, quale metodo usare per affrontarlo ?