Full Idea
One addition to the truth functional account of conditionals is that A be somehow relevant to B. However, sometimes we use conditionals to express lack of relevance, as in 'If Fred works he will fail, and if Fred doesn't work he will fail'.
Gist of Idea
We can't insist that A is relevant to B, as conditionals can express lack of relevance
Source
Frank Jackson (Conditionals [2006], 'Possible')
Book Reference
'Blackwell Guide to Philosophy of Language', ed/tr. Devitt,M/Hanley,R [Blackwell 2006], p.214
A Reaction
This certainly seems to put paid to an attractive instant solution to the problem.