Wiki page unless changed
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.
> 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.
mu'o mi'e xorxes
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