ABSTRACT
When we are told something that is startling or unpleasant we may be moved to ask our informant: ‘How do you know that?5 Usually such a question is a demand for reasons: we want to know the grounds for the statement rather than to inquire what were the processes of thought through which our informant was led to make the statement in question; we are asking for some assurance; we are not willing to accept the statement without evidence. The sort of answer that would satisfy such a questioner would take the form: ‘Because it (i.e. what was originally stated) follows from so-and-so.5
