This paper approaches the subject of consistency by trying to establish certain differences between the rôle of consistency with respect to assertions, and its rôle (and that, of course, of inconsistency) in discourse other than assertions: the example I treat in some detail is that of imperatives. The thesis I advance here is that while ‘consistent’ and ‘inconsistent’ apply to imperatives all right, the consequences and significance of this are different and less fundamental than with assertions. I try to make a similar point, briefly, about rules. The later part of the paper tries to sketch, I fear very vaguely, a direction for explaining the differences brought out in the first part; this involves taking seriously the platitude that assertions are concerned with truth. This leads me to realism; having merely arrived at it, I stop, except for some considerations about ethics which I hope may suggest that the direction I have taken is at least a direction. So ‘Consistency’ is the name of the subject, and ‘Realism’ the name of a problem; I hope the discussion of the subject will suggest that there is that problem, where I think it is.

I shall start with some considerations about consistency and inconsistency between imperatives. This is, in a number of respects, a well-worn subject; I shall rely on this fact to the extent of passing lightly over some issues which demand, and have received, more precise treatment.