The side-discussion about understanding and the prinicple of charity (see article and comments here) does not seem finished to me. In this context, Gadamer comes to my mind: He speaks about the prejudice of perfection (of sense) that gets irritated as soon as the attempt to consider the text as true breaks down (Wahrheit und Methode, Bd. 1., ed. by Mohr, Tübingen 1990, p.299). That such a breakdown is possible indicates that “understanding is primarily to understand the case” and not the text as sequence of strings. In understanding the case, it is possible that something resists to fully accept the text, because the text cannot (always) create the topic/case it is talking about. The resistance could stem from (fruitful) prejudices or because of explicitly formulated judgments. Anyway, if the attempt to consider the text as adequate breaks down, it can lead – as a plan-B – to the effort ‘to understand’ the opinion of the other psychologically or historically.