 A reason, for Stevenson, is “any statement about any matter of fact which any speaker considers likely to alter attitudes” (1944, 115). “Whether this reason will in fact support or oppose the judgment will depend,” Stevenson says, “on whether the hearer believes it, and upon whether if he does, it will actually make a difference to his attitudes; but it may conveniently be called a reason (though not necessarily a ‘valid’ one) regardless of whether it is accepted or not” (1944, 115). Thus, a reason is a statement whose content, if believed, is causally relevant to altering attitudes. (This may seem like a very surprising account of what it is to be a reason for some attitude; see also  Section 5.1,  below.)