I'm kind of embarrassed to admit that, despite the fact that Koa is supposed to be an IAL and was structurally inspired partly by Tok Pisin example sentences, I didn't actually read a reference grammar of a creole until about 10 years into the design process.
My obsession with Bislama over the past few years started me on the road to rectifying this, and I've started poring over actual linguistic surveys of pidgins and creoles to try to really understand what's likely to make a language easy to learn.
Of course, at this point Koa has its own identity/structure/momentum and it's likely that there are going to end up being some irreconcilable areas. I've worked to smooth out or reduce some of them, but the fact is that the basic idea behind Koa is quite philosophical, and as such unlikely to be reflected in, for example, real-world Creoles.
Nonetheless, it may occasionally be necessary to sacrifice particular parts of the Koa identity in favor of clear optima that would otherwise be unreachable. One of these possible situations has very recently become apparent in the area of tense/aspect/mood.
To bring us up to speed, as of this moment Koa officially has the following categories:
Ø = aorist/timeless/stative
ma = imperfective
si = perfective
lu = future/volitive
io = "translative"
va = habitual
mi = inchoative
su = cessative
ha = irrealis
vi = imperative/jussive
There's been a certain amount of wiggling here in the irrealis department (principally with lu and ha), but on the whole I've been very happy with this system, the core of which has been intact since the early 2000's at latest. The thing is that, for better or for worse, creoles are fairly unified in the TAM categories they mark, and this is not how they do it.
This article gives a sense of what you would expect to see, at least based on the body of creoles we have at our disposal to examine. Of course, with very few exceptions these creoles are based on Indo-European languages, and it's hard to know how many of these similarities are due to this rather than some kind of cognitive universal. For the moment, let's assume for the sake of argument that the TAM system of the existing creoles does represent an ideal of some kind, especially since they did end up with this regardless of substrate.
To sum up the article, and incorporating one category from my own research, a typical TAM spread would look something like this:
• unmarked (aorist for statives, often past tense for actives)
• irrealis (future/conditional)
...plus combinations. It happens that we could potentially map these right onto our existing Koa particles:
Ø = aorist (statives), past etc. (actives)
ma = imperfect/nonpunctual
si = anterior
io = completive
lu = irrealis (future/conditional)
I would like to reserve the right to maintain the distinction between imperfect and habitual, and there's no reason to abandon the other telic aspect markers or jussive, so we'd also throw in:
mi = inchoative
su = cessative
vi = imperative/jussive
Note that the unmarked form for active (non-stative) verbs tends most neutrally to indicate completed past tense, but could also be present/future/etc. given the right context. The point is that, unlike traditional Koa, this form refers to a real event that happened (or is happening), and where that occurs temporally depends on what's most likely for a narrative involving that verb, and/or context.
So what would this mean for Koa? Mainly just a different distribution of TAM particles:
ni na ipo sahi
1SG NEG drink wine
trad "I don't drink wine"
new "I didn't drink wine" or "I'm not drinking wine," depending
ni na si ipo sahi
1SG NEG PERF/ANT drink wine
trad "I didn't drink wine"
new "I hadn't drunk wine"
ni na va ipo sahi
1SG NEG HAB drink wine
trad "I don't usually drink wine"
new "I don't drink wine" or "I don't usually drink wine"
ni na ma ipo sahi
1SG NEG IMP drink wine
trad "I'm not / I wasn't drinking wine"
new "I'm not / I wasn't drinking wine" or possibly "I don't go around drinking wine"
With stative verbs, in other words verbs for which there's no change of state in any participants, things lay out a bit differently:
ni nae ka kohúla
1SG see DEF dance
trad "I'm a person who goes to see the dance" or "I see the dance"
new "I see the dance"
ni si nae ka kohúla
1SG PERF/ANT see DEF dance
trad "I saw the dance"
new "I saw/had seen the dance"
ni va nae ka kohúla
1SG HAB see DEF dance
trad "I make a habit of seeing the dance"
new "I see the dance sometimes" or "I make a habit of seeing the dance"
ni ma nae ka kohúla
1SG IMP see DEF dance
trad "I'm looking at the dance"
new "I'm looking at the dance" or "I always see the dance"
It makes sense: why not make the formally unmarked form the one whose meaning is also least marked? This becomes particularly, even indispensably useful, with verbs involving a process. These posed a major dilemma for traditional Koa in an effort to avoid Esperanto-style arbitrariness.
Take the concept of waking up. Should the root morpheme be an adjective describing the state of awakeness? Or should it be verbal, describing the process of waking up? In other words, should ta vene mean "she's awake" or "she wakes up?" I tried to come up with a decision-making flow chart along the lines of cultural importance of the process versus the completed state, but in the end it was going to be a largely arbitrary choice.
If we take change-of-state verbs as basically past-tense by default -- in other words, the unmarked form denotes a completed process -- this problem completely goes away: for example, we have ta vene "he is awake" or "he woke up," which are after all approximately the same thing, ta io vene "he already woke up / is already awake" to emphasize the completedness of the process, and ta ma vene "he's waking up" to emphasize the imperfectiveness of the process.
This works with the whole conceptual family, and obviates the need to make any decrees from on high. Check out how nicely these verbs lay out when used adjectivally, without needing aspect particles:
lopu "finished, over"
Furthermore, we could also say that this kind of verb is hermaphroditic with respect to transitivity: in other words, we could allow ta vene ni "he woke me up" and avoid a whole other hornet's nest of deciding which valence should be neutral. Suddenly the language is much, much easier to learn, not to mention design...
It also helps tidy up the difference between e.g. "see" and "look." Context will still play an important role, but rather than the meaning being inferred completely from context, there will also be a different relationship of particle structure to aspect which will help resolve the intent:
ni nae ka hapi
1SG see DEF ant
"I see the ants" OR "I looked at the ants"
ni ma nae ka hapi
1SG IMP see DEF ant
"I'm looking at the ants" OR "I'm always seeing ants"
ni si nae ka hapi
1SG ANT see DEF ant
"I saw the ants" OR "I had looked at the ants"
In sum, it seems like this is a really good idea: it both helps me out of all kinds of aspectual binds, and makes the system more creole-like in keeping with the aims of the design. The question, though, is whether this will integrate with the foundational modular systems of the language: however great it seems, I can't keep it if it would wreak havoc with everything else.
The main area of concern is with the unmarked forms. A lalu would now no longer refer to one who can/might/will sing, but rather one who really did or does sing. I don't think this is a problem, though:
"he sang" OR "he is a singer"
...in the sense that he can be called that because of some singing which he has done, is doing, or will do. So VP's are okay; how about adjectives?
a mola lalu
INDEF bear sing
"a singing bear, a bear singer, a bear who sings/sang"
Seems totally fine. And the nominal form is unproblematic as well.
Well, then, there we have it: looks like there's no reason not to make this change. The biggest thing to get used to will be using si a whole lot less (and actually, I'll need to devote a post to the question of when to use it -- my current creole research will help with this). I'm not completely sure what all the repercussions may be, so stay tuned for future agonizing...