Reading Lawrence Kaplan on Iraq reminded me of an odd grammar puzzle. Sez Kaplan:

The question, then… is, when and if things turn out well in Iraq, will journalists even be able to recognize it?

Why do people say "if and when"? (Or, in Kaplan's case, "when and if".) "If..." and "when..." are two entirely different logical/grammatical constructs, and the whole point of saying "if" is that there might not be a "when." Clearly both won't always pertain, so it should be "if or when." But people don't say that. Why?

UPDATE: Good cases for and against in comments. For the record, that lord of usage, H.W. Fowler, said back in 1908: "This formula has enjoyed more popularity than it deserves," and then dissects it. Splendid! Meanwhile, the olumbia Guide to Standard English says that charges of "faulty parallelism" against the phrase are "unwarranted". (But why?) You could also argue that it's a redundant way of speaking. My solution: Use "in the event that..."