Conditionals and mental-space set-ups

Grammars and textbooks seem unanimous in starting their treatment of English conditionals with certain classes of forms. Any textbook will tell you how to say If it rains, they'll cancel the picnic or If I'd done my homework, I'd have done better on the test; but most of them never get as far as If you're so smart, why aren't you rich? or If you're free this evening, there's a good movie on. Further, it is the same class of “central” conditional functions which seem to be used crosslinguistically in identifying a particular form as a conditional. That is, a grammatical form which conventionally does the same job as If it rains, they'll cancel the picnic is ensured a conditional label in a grammar of the relevant language.

Although we don't intend to stop with this limited set of conditional functions, we are starting our examination of conditionals with familiar examples like these. There is a good reason for the salience of this class of functions in the minds of grammarians: the conditional predictive function is an important one in human cognition and communication. As an initial non-technical approximation, let us say that by predictive conditional we mean that someone is predicting something (e.g., picnic cancellation), but only conditionally upon some unrealized event (e.g., rain happening tomorrow). Every language has some way of expressing this function.