Past tense is not past tense

I took part in a wonderful Dagstuhl workshop this past February on translating morphologically rich languages. (Yeah, I also don't really know why I was invited :P.) But many thanks to Alex, Kevin, Philipp, Helmut and Hans for inviting me. I had a realization during this workshop that I thought I'd share. It's obvious in retrospect, and perhaps in front-spect for many of you. Much of this came up in the discussion with Bonnie Webber, Marion Weller, Martin Volk, Marine Carpuat, Jörg Tiedemann and Maja Popovic, and Maja deserves much credit for her awesome error analysis tool that helped shed some light on German.

One thing you commonly think of when translating into a morphologically rich language is that there's stuff you're going to have to hallucinate. Really this isn't an issue of morphology per se, but just that this is one place where it's obvious. For instance, even going from English to French you'll have to hallucinate gender on your determiners (un versus une and le versus la) that's unmarked in English. Or when going from Japanese (which roughly combines present and future tenses into a single tense) to English, you'll have to hallucinate "will" at appropriate places.

An abstraction that I think was pretty widespread among the initial discussions in the workshop was that if you're going from language X to Y, there are basically two options:

1. Phenomenon foo is explicit in Y but implicit in X, and therefore you'll have to hallucinate it (i.e., tense is explicit in English but not in Mandarin)
2. Phenomenon bar is explicit in Y and also explicit in X, and so you can just copy it.

The problem is that (2) is just false, even for things that you think it might not be false for. That is to say: Just because two languages explicitly code for something that we give a consistent (linguistic) name to, doesn't mean that they code for it consistently.

Okay, so you want examples.

An easy example is gender. I've been well assured that, for instance, French and Russian both have explicit gender. But just because some noun (eg moon/lune) is feminine in French doesn't mean it's also feminine in Russian. (In fact I think it's neuter.)

You might argue gender is a stupid thing to pick because it's essentially an artificial encoding of who-knows-what.

How about tense. That clearly has a semantic interpretation (did something happen in the past, the present or the future) and so if languages X and Y both express some particular tense, they must be consistent in how they do it.

Wrong. Now my memory is getting a bit shaky, but my recollection is that, for instance, in newswire text, it's very common in German to refer to things that have happened in the past in present tense. To English speakers this is a strange convention (we tend to refer to such things in past tense), but it doesn't have to be so. And of course English has it's own idiosyncrasies: see the plight of the native German speaker who cannot understand English tense usage in (New Zealand) news articles.

Part of this is probably because tense, even in English, is a pretty slippery concept. We (native English speakers) have no problem using present (or progressive) tense to refer to things that happened in the present (John runs) the past (so yesterday I'm running to the store and a hamburger falls on my head!) or the future (my flight leaves at 8:00 tonight).

Another easy example is definiteness (thanks to Kevin Knight for this inspiration). Again, our high school English teachers tell us that "the" (+Definite) has to refer to something that's already been introduced into context. I just went to cnn.com, clicked on the very first link, and the first sentence is "The boss resigned under pressure and other Veterans Affairs managers are likely on the way out." Ok you could argue that "The boss" is already in the context of the US news media (this is an article about Shinseki) but it's nonetheless very common to see (English) entities introduced using "the" and the precise rules that govern this may or may not be consistent across other languages.

The long and short of this is: I like the fact that translation into morphologically rich languages makes us pay attention to linguistic divergence. But that doesn't mean that divergences aren't there even when languages express the same set of linguistically-named phenomena. Usage can vary dramatically, be it for conventions, socio-linguistic reasons, or other things that are hard to pin down. It's just that by focusing all our energy on a very particular convention (newswire, parliament), we can pretty easily learn these mappings because there's no variability. Add some variability and we're hosed, even for languages with the same set of (overt) markings.