Wiki page unless changed
wrote:
>
> pc:
> > I'm not sure what you mean by "complement,"
> > appparently the sentence after the "unless"?
> But
> > that doesn't seem to fit the usual cases: "He
> > will come unless he gets caught in traffic"
> which
> > is neither obviously false nor even unlikely
> but
> > merely setting up an explanation in case the
> > other sentence turns out to be false.
>
> "He will come" is the default case, "he gets
> caught
> in traffic" is the exceptional case. In the
> default
> world/situation, he comes. In other than the
> default
> world, it may be the case that he gets caught
> in
> traffic and does not come.
>
> The sentence does not mean the same as "he will
> get
> caught in traffic unless he comes", so plain OR
> won't
> do it.
Yes; some mark for the "exceptional" case (just
less common or less what is desired or expected)
is needed. the point is always just tht it is
not {da'i}. I think the use of worlds talk here
is taking things a bit too far, unless you want
different occasions to be different worlds even
though both may be in the real world.
>
> > What does seem to be the case is that there
> are
> > two uses of "unless," one purely factual, the
> > other with an added fillip, presumably the
> same
> > one that occurs also (though in a negative
> > presentation) in the conditional cited above,
> > emphasizing the truth (or falsity) of one
> factor
> > by the obvious falsity of the other.
>
> Yes, and both "if" and "unless" in the
> non-emphasis
> case usually carry an additional component of
> causality
> which is absent in the purely truth functional
> connective.
Is the causal factor semantic or merely
pragmatic? In any case, something should be said
to mark off the unemphatic case.