Are "wenn" and "falls" really always interchangeable in case of a conditional? [duplicate]

Question

The question is only about the case, when both conjunctions are used as a conditional (leaving the possibility to use "wenn" as temporal aside).
Let's start off with an example:

"Falls ich jemand anders wäre, würde ich woanders wohnen."

While the same sentence with "wenn" sounds fine to me, this one doesn't. Somehow I feel in case of "falls" the condition must be actually fulfillable.

What I believe: "wenn" - works even for fantasized conditions
"falls" - the condition must really be an option at the time of the phrase

Am I wrong?
I would really appreciate acknowledged and reliable sources in both cases.

Answer 1

They are not completely interchangable. It depends on your intention as speaker: in some contexts constructions with „wenn“ bear a temporal and a conditional intention (mostly both), while „falls“ is reduced to the conditional.

Please consider following examples:

Wenn ich zurück komme, heiraten wir.

vs.

Falls ich zurück komme, heiraten wir.

The second sentence induces some kind of uncertaincy, read „In case I come back, we will marry.“; while in the first example this reading is not this much obvious.

On the other hand, the first sentance can explicitely mean “The time I come back, we will marry” while this reading is – if anything – only implied in the second example. The differences are subtle but it would be weird to use „falls“ when you talk about a time being or to use „wenn“ to emphasise uncertaincy.

Edit: it may be comparable to the difference between “if” and “when” in English:

We talk about it if you return

vs

We talk about it when you return

Answer 2

You are wrong. The difference in usage of wenn and falls is personal style.

Source: Canoo.net

But the personal style might also say, that they are not interchangeable in irreal conditional sentences.

Source: YourDailyGerman

Answer 3

A standard English translation for "wenn" is "if." That is a hypothetical. On the other hand, "falls" translates roughly into "in case." There's an element of fear, or at least doubt, here. They are similar but not quite the same.

Answer 4

Your analysis is correct. "Falls" does translate literally to "in case", so if the condition is not fulfillable, like in your example, then "falls" is technically not the correct choice. While it doesn't sound totally wrong, I don't believe that a native speaker would use that word here.

Germans often use this to decide whether to use "if" or "when" in English, i.e. to distinguish the temporal wenn from the conditional wenn. The theory goes that, if you can replace the German wenn with falls, you should use the English if, otherwise you use the English when. Obviously this only works properly for fulfillable conditions but "falls" still sounds ok (or at least better than thinking of it as a temporal clause) in German.