Common is not a natural language, but it is spoken natively by hundreds of millions of people and plainly meets the minimum requirements for human speakability. As such, it is subject to the same typological and syntactic analysis as a natural language. This article will delve deeper into a couple of key characteristics of Common - its ergative morphosyntactic alignment and  how it identifies and handles the syntactic pivot of a sentence, which in natural languages is linked to morphosyntactic alignment.

This article will look into these topics in more depth than you would typically need just as a learner, although the particular subject touches on points that are front in centre in many learners' greatest difficulties in learning Common.

Ergativity

Common is an ergative language, like only about a sixth of the world's languages, but that drastically overestimates the number of speakers of natural languages with high degrees of ergativity. It is impossible to get reliable figures on the numbers of native speakers of different languages today, especially languages other than Common, which the NWO doesn't bother to track. But pre-Collapse, no language with dominant ergativity even cracked the top thirty.

To get a sense of what it means for a language to be accusative or ergative, refer to this article on morphosyntactic alignment. Basically, accusative languages are like English - the subject of an intransitive verb is treated the same as the agent (subject) of a transitive verb. Ergative languages like Common instead treat the subject of an intransitive verb the same as the object of a transitive verb.

There is a reason why we talk about 'degrees' of ergativity, though - most languages with ergativity have some degree of split ergativity, where verbs use the ergative alignment in some contexts and accusative alignment in others. The degree of prominence of ergativity in a language can therefore vary, but a language is spoken of as being 'ergative' if ergative alignment is very predominant in its morphosyntax.

Common's ergativity poses a notorious struggle for second-language learners. A way of thinking about ergativity that often seems to help is to think of languages like this as being focused on the experiencer rather than the subject.

Common does have split ergativity, but the split is between morphological and syntactic ergativity. Morphologically, Common is completely ergative. Ergativity is mediated completely through case marking on noun phrases via the case of the article. Ergative alignment is observed for all tenses, aspects, etc.

Syntactically, however, Common is accusative. Consider the following examples, with Agent (A) and Patient (P) of the transitive verb and the Sole argument (S) of the intransitive verb marked:

Ja pikki (A) tene slek a skitrem (P)
the(ERG) cat hit(NP.PF) eat the(ABS) mouse
The cat has eaten the mouse.

Compare this to:

A pikki (S) se hitaj.
the(ABS) cat stand(NP.IM) sleep
The cat is sleeping.

You can see that morphologically, Common treats S the same as P - they are both in the absolutive case. But syntactically it treats S the same as A - although Common has free word order, it does have a preferred word order, which is SVO, and in that word order, both A and S appear before the verb. S is treated like A syntactically.

The fact that Common is syntactically accusative may relate to yet another of its strange features - it is an SVO language as its default, preferred word order, yet virtually no natural ergative languages have this word order, overwhelmingly preferring verb initial or verb final syntax.

With natural languages there is no 'why' to this - human languages seem to prefer the accusative alignment overwhelmingly, and even significantly ergative languages tend to have some accusativity. However, ergative alignment works perfectly well, and among natural languages is simply part of the wonderful and endless variety of human linguistic ingenuity.

For Common, however, as a constructed language, 'why' is a legitimate question. It is an especially reasonable question to ask when you consider that as a constructed language, Common could have been anything, and there have been numerous attempts at a constructed international language optimised for ease of learning for the majority of people. So why does Common have features, like ergativity, that are perversely counter-optimised to be as hard as possible to the most people?

The answer is in the fact that Common was designed by Peter K. Davidson not for international communication but for a screenshow. Davidson was restricted in his design phonologically because English-speaking actors had to be able to pronounce his language without butchering it too badly, so he couldn't use sounds that were too exotic, but it was irrelevant to anyone if the actors actually understood their lines, so Davidson had more room to play with grammar. Ergativity, being an uncommon language feature, was probably chosen by Davidson simply because it is unusual. He probably simply thought it was 'cool', and in my opinion, it is likely he didn't actually understand it very well. And as simple as that, a decision was made that wound up afflicting the entire human race.

Syntactic Pivot

That is as good a segue as any into the topic of syntactic pivot in Common. Click this link for a more involved explanation of what syntactic pivot is. Basically, a syntactic pivot is a verbal argument around which a verb 'revolves' in a given language. It has implications for what arguments can be omitted in coordinated propositions. Specifically, the syntactic pivot is typically the argument that can be left out of the second clause.

To see how this works, consider the following example in English:

1. The cat saw the mouse.
2. The cat killed it.
The cat saw the mouse and ___ killed it.

In English, the subject of a verb is the pivot, and we can see in this example, when these two transitive sentences are coordinated with 'and', the cat is the argument that can be omitted from the second clause. The following would not be grammatical, or would at least not convey the desired impression that the cat killed the mouse clearly and idiomatically:

*The cat saw the mouse and the cat killed ___.

Or take an intransitive verb in the second clause - in the sentence, 'The cat saw the mouse and ___ purred', it is clear that the missing argument is the cat, not the mouse. If the verb were 'squeaked', grammatically it would still seem like the cat squeaked, however improbable an act it might seem.

Ergative languages don't necessarily work like this - in ergative languages, often the absolutive argument is the pivot and a sentence. 'The cat saw the mouse and the cat killed ___' would actually be the grammatical form, assuming the language permitted arguments to be omitted at all.

Common is a little hard to pin down because of its strange and unnatural structure. As far as I'm aware, no natural language does what Common does and grammatically declares the valance structure of all of its verbs without having any kind of specific verb-argument agreement, and Common's very pro-drop syntax where literally any argument of any kind of verb can be dropped is very nearly as unusual.

However, in practice, native speakers do show a clear tendency around syntactic pivot, and it is actually accusative. In other words, Common uses a subject pivot rather than an absolutive pivot. Take the following example:

1. Ja pikki teo lawf a skitrem.
the(ERG) cat hit(P.IM) chase the(ABS) mouse

2. Ja pikki teo slek a skitrem
the(ERG) cat hit(P.IM) eat the(ABS) mouse

The coordinated form most speakers will prefer is:

Ja pikki teo lawf a skitrem hanja ___ teo slek a spe'n.

While both arguments could be omitted from the second clause and it would be perfectly grammatical Common, the preferred default will be to use a phrase like 'a spe'n' to call back to the mouse as the antecedent for rhetorical purposes and to omit the subject. But if Common used more of an absolutive pivot, the preferred form would look like:

*Ja pikki teo lawf a skitrem hanja ja spe'n teo slek ___.

This is actually a grammatical sentence as well, but a Common speaker is less likely to produce it. If Common used an absolutive pivot, though, this would be the preferred form.

Consider what happens when one of the sentences is intransitive. Example:

1. Ja pikki teo lawf a skitrem.
the(ERG) cat hit(P.IM) chase the(ABS) mouse

2. A pikki sea cih.
the(ERG) cat stand(P.IM) laugh

The coordinated form would look like:

Ja pikki teo lawf a skitrem hanja ___ sea cih.

This is, 'The cat chased the mouse and laughed.' In English, it is clear that the cat laughed. In a language with an absolutive pivot, the listener would assume that the mouse laughed. A Common speaker, however, automatically assumes that it was the cat that laughed, so here again we see subject pivot and overall accusative behaviour in Common with regard to syntactic pivot.

Common's ergative morphology and accusative basic syntax are designed features of the language, but the fact that Common uses a subject syntactic pivot is not something that was designed into the language but which arose spontaneously and was documented after the fact. Davidson, in fact, seems to have had a relatively elementary grasp of syntax, and largely allowed this aspect of the language to sort itself out.

Semitransitive Verbs and Syntactic Pivot

The Common 'semitransitive' valance is a strange conceit that may be unique to that language. A 'semitransitive' verb has an absolutive subject which can shade into being an actual agent, and a dative indirect object. In Common, verbs of motion or emotion tend to be semitransitive, with the absolutive subject being the mover or feeler and the dative indirect object being the destination or the object of the emotion.

Semitransitive verbs really show that Common is subject pivot as opposed to absolutive pivot. Take the following example:

A pikki noxa triju ija skitrem.
the(ABS) cat go(P.IM) see the(DAT) mouse

Ja pikki teo lawf a skitrem.
the(ERG) cat hit(P.IM) chase the(ABS) mouse

The coordinated sentence is:

A pikki noxa triju ija skitrem hanja ___ teo lawf a spe'n.

There is no question to a Common speaker that the cat is both the seer and the chaser, even though it would take a different case in each clause (it would be ergative in the second clause). And Common speakers are more inclined not to omit a reference to the non-pivot argument in the second clause - although it would be perfectly grammatical to do so.

Antipassives and Syntactic Pivot

To summarise the point, Common does not actually use its antipassive verb forms to coordinate syntactic pivots. This section will explain what that means, go into why, and show how Common would handle the problem instead.

A major use of the passive or antipassive voices in languages that have them is to take advantage of the ability to make the syntactic pivot the same in two sentences the speaker might want to coordinate. It may be easier to see how this could work by seeing how it is done in English. Take the example from before, but instead of the cat killing the mouse, the mouse pulls off a surprise upset and kills the cat - perhaps it has a tiny machine gun.

1. The cat saw the mouse.
2. The mouse killed it.
*The cat saw the mouse and ___ killed it.

Now the coordinated sentence doesn't work - the two component sentences don't have the same pivot, so the coordinated sentence gives the wrong idea about who did what to whom. It would be necessary to state it explicitly, like, 'The cat saw the mouse and the mouse killed it.' But it would be possible to preserve the subject deletion, if the speaker wanted, by reframing sentence #2 using the passive voice:

1. The cat saw the mouse.
2. The cat was killed by it.
The cat saw the mouse and ___ was killed by it.

Now the two sentences have the same syntactic pivot and can be coordinated in a way that allows the subject to be deleted from the second clause.

Accusative languages tend to have a passive voice. Ergative languages tend to have an antipassive, instead. We can sketch out a little bit of how this looks using English in a simplified way. The case of the noun is in brackets - (E) for ergative and (A) for absolutive. We'll use (Prep) for some kind of non-core-argument prepositional case. The active verb form will be marked with (AC) and the antipassive verb form will be marked with (AP)

Active: Clara(E) is eating(AC) the pie(A).
Antipassive: Clara(A) is eating(AP).
Optional non-core patient: Clara(A) is eating(AP) of the pie(Prep).

What this would allow is for an ergative language that uses the absolutive-case verb argument as the syntactic pivot to move the ergative agent, which can normally never be the pivot, to the pivot position and construct coordinated sentences with the pivot deleted in the second clause that would not be possible otherwise, expanding the speaker's rhetorical options.

Common has an antipassive. So, does Common use it to set up syntactic pivots in the same manner that English uses its passive voice or many ergative languages do their antipassive?No it does not. The reason is that it wouldn't work - the antipassive in Common works as described above, promoting the ergative agent of a transitive verb to the absolutive subject of an intransitive verb that can now only specify its patient periphrastically, so it would work very well if Common used the absolutive as the syntactic pivot. But Common actually uses the subject as the syntactic pivot, and Common is syntactically accusative.

Let's illustrate this with an example above that is flipped around similar to how we illustrated the use of the passive for English. In this case, the pivot is in bold.

1. Ja pikki teo lawf a skitrem.
2. Ja skitrem teo slek a pikki

The coordinated form with subject deletion in the second clause is:

Ja pikki teo lawf a skitrem hanja ___ teo slek a spe'n.

In Common, it's perfectly grammatical to delete any of the arguments to the verb and allow them to be understood from context, but in a coordinated construction like this, the subject of the second clause will tend to be automatically understood to be the syntactic pivot, unless a different subject is explicitly stated.

To avoid this misunderstanding in Common, a different mechanism would be employed. First of all, the coordinating conjunction 'hanja ('and-then') would likely not be chosen - instead, the speaker would likely use 'joku' ('but', 'however'), which signals to the listener that the next clause is going to go against their expectations. Also, the unexpected subject would likely not be dropped. So an idiomatic sentence that conveys the same thing as 'The cat chased the mouse and was eaten by it' would be:

Ja pikki teo lawf a skitrem joku ja skitrem teo slek a spe'n.
The(ERG) cat hit(P.IM) chase the(ABS) mouse but the(ERG) mouse hit(P.IM) eat the(ABS) [antecedent].

The 'a spe'n' antecedent marker, much loved for rhetorical purposes in idiomatic but casual High Common, could be deleted. While it is grammatical to delete 'ja skitrem', 'the mouse' from the second clause, it generally wouldn't be, because its presence is explaining why the speaker used 'joku' as the coordinating conjunction and removing it would still leave confusion. It is highly likely to be kept.

As an aside, in very formal High Common, where 'spe'n' is still viewed as a little too colloquial and lazy, there are a few alternatives a speaker might use:

1. Ja pikki teo lawf a skitrem joku ja skitrem teo slek a spet yn.
2. Ja pikki teo lawf a skitrem joku ja skitrem teo slek.
3. Ja pikki teo lawf a skitrem joku ja skitrem teo slek a.

The first form, 'a spet yn', meaning approximately 'the this one', is where the contraction 'a spe'n' actually comes from and is well-liked in classic rhetoric. The second form is perfectly acceptable and might be seen in any speech register.

The third form is technically fine according to schoolbooks and the design of the Common language itself - after all, Common articles are supposed to also be pronouns, and the 'a' in this case means 'it'. However, native speakers don't like bare third person pronouns and tend to not speak like that. The 'a spe'n' or 'nothing' forms are far more likely, and in extremely casual speech (more casual than using 'a spe'n'), you might hear:

Ja pikki teo lawf a skitrem joku ja skitrem teo slek a'n.

Here the speaker has added the dummy term 'yn' to the third person pronoun and contracted it on as a suffix. In non-careful speech, this type of form is at least as likely as the two licit, formal options or 'a spe'n'.

Conclusions

Common is an ergative language overall. Despite not being purely ergative, ergativity is prominent enough to be considered to characterise the language overall.

Common is specifically morphologically ergative, where it is actually completely ergative. However, Common is syntactically accusative. Furthermore, while Common has free phrase order due to case marking, it prefers SVO word order, which is very strange for an ergative language.

Common's syntactic accusativity extends to syntactic pivot, meaning that its antipassive voice is not useful for managing syntactic pivot. Instead, Common prevents misunderstandings by explicitly stating the subject in both clauses and/or by using a coordinating conjunction, 'joku', that signals that the next statement will run counter to expectations.