My point is that the prior under which you interpret the text is shaped by the expectations about the source of the text. If the text, taken alone, is seen as likely meaning something that you didn't expect to be said, then the knowledge about what you expect to be said takes precedence over the knowledge of what a given piece of text could mean if taken out of context. Certainly, you can't read minds without data, but the data is about minds, and that's a significant factor in its interpretation.