I ran across the following strange set of instructions on IRS Schedule EIC. They had a column for each child. Line 3 says:
If the child was born before 1985 --
a. Was the child under age 24 at the end of 2003 and a student?
Yes (Go to line 4.) No (Continue)
b. Was the child permanently and totally disabled during any part of 2003?
Yes (Continue) No (The child is not a qualifying child.)
It seems to me that the proper answers for both and a and b for our children are no, taking the questions in isolation from the antecedent above. Yet they don't intend us to answer that way. They intend us to skip those questions. If we take it as a material conditional, we get this result. Any material conditional with a false antecedent will be true. So should I check Yes for both questions? If I do, they'll look above and see that our kids were born in 2001 and 2002 and investigate me for tax fraud. They don't want me checking Yes. They also don't want me checking No. Otherwise, I wouldn't be able to continue past 3b. They want me to skip it, as if they think the conditional has no truth value.
This is good evidence that ordinary conditionals in English don't always function logically the way material conditionals do (though sometimes they do -- e.g. 'if that story is true, then the Pope's Italian' where the speaker clearly believes the story is false). Most philosophers who work on conditionals already believe this, so this isn't anything new. I just thought it was an interesting place to see evidence for this.