Indicative versus subjunctive in future conditionals
The first of these is assertable, given normal beliefs about the world, and the second is not, so the ‘did/would have’ contrast seems to mark a difference in meaning. I’ll call these ‘Adams pairs’, since the first examples were due to Ernest Adams. 1 I’ll assume familiarity with the basic use of Adams pairs to make an indicative/subjunctive distinction. Most people on absorbing the distinction are inclined to classify many future tense conditionals, such as