So let’s talk about space.
In the vast expanse of human language, a single sentence can seem pretty insignificant.
But the rules we use to build them up also have the power to bind them together, letting
even the simplest of clauses extend outward almost without limit.
So, what is it about these rules that makes our linguistic universe so special, and what
does it look like when we run out of room?
I’m Moti Lieberman, and this is The Ling Space.
Simple sentences are made up of a single clause, and so they group together just one subject
and predicate at a time.
So, you’ve got sentences like “Detective Miller is looking for Julie Mao,” or “Amos
doesn’t trust him” — each one with a subject that the sentence relates to, and
a predicate that goes on to say something about that subject.
Of course, like most things, sentences aren’t always simple.
Many languages have words like “and” or “or” and “but,” which are able to
co-ordinate phrases that share a category.
So, these hook up two noun phrases, like in “James and Naomi,” or a couple of verb
phrases, as in “make yourself useful or get off the ship.”
Those kinds of words work on full sentences, too; we can take some of our simple sentences
from before and just string them together as long as we want... or at least, until we
run out of patience or lose our place.
This way of mashing together sentences is probably pretty familiar, but there’s another,
deeper way that we can put them together, too.
It turns out that subjects and predicates can actually contain clauses themselves, and
those can have their own little subjects and predicates inside, like Russian nesting dolls.
And this is thanks to one of language’s most defining characteristics: recursion.
Simply put, something is recursive if it somehow contains or makes reference to itself.
So, like those dolls, or a triangle made up of other triangles. Language is recursive,
because the rules that construct sentences can loop back on themselves.
A phrase like “up on the bridge” has one prepositional phrase nested inside another,
and English has a lot of complex verb phrases, too, like “having been discovered.”
Recursion ensures that, in principle, there’s no upper limit for how long expressions can
be, or how many you can sandwich inside of each other.
So, what exactly does it look like when whole sentences recurse?
Let’s get a close-up.
Take the sentence “Fred Johnson believed that the insurgents had refused to surrender.”
One way to describe its structure is to just stick one full clause, or tense phrase, inside of another.
The snag here is there’s no room left over for “that”!
It’s not really a part of the verb, and it can’t really be part of the tense phrase either,
since “that the insurgents had refused to surrender” can’t stand alone as a sentence.
“That” doesn’t really have anywhere in the tree to call home.
In order to make room for this class of word, linguists have supposed that embedded clauses
actually come packaged inside CPs - complementizer phrases that serve as living quarters to
complementizers, which is what we call words like “that,” “whether,” and “if.”
These complementizers act as a kind of ‘interface’ between the verb above and the clause below;
they encode information about whether the clause is making a statement, by using “that,”
or posing a question, by using “whether,” as in “Fred Johnson wondered whether the
insurgents had refused to surrender.”
Verbs that embed complementizer phrases can even have different requirements about whether
or not the clause that follows them has tense, as in “Fred Johnson wanted for the insurgents
to surrender,” with “for” in place of “that.”
CPs, then, give us just enough leeway to explain how we can embed sentences, without having
to make any big changes to the X’ theory that we've been developing so far.
And they often live inside verb phrases, as one of the ways a predicate can contain a clause.
But it isn’t only after certain verbs where we find these sorts of so-called complement clauses.
They show up after some nouns too, like “fact” or “belief” or “idea”.
So, “Fred Johnson’s belief that the insurgents had refused to surrender,” or “the fact
that they’d done so.”
And we can get clauses living inside subjects as well.
Another kind of embedded clause we see after nouns is the relative clause.
Relative clauses look a lot like the structures we've seen so far, but with one of their pieces missing.
In subject relative clauses, the first part’s left out, and filled in by whatever the clause is attached to.
So, “the people that live on the station" and not “the people that they live on the station".
Object relative clauses are pretty much the same, but with the end left out instead, and the
gap again understood to refer to the noun at the start, like in “the planet that Alex calls home".
So these are ways for subjects and predicates to contain clauses, too.
But both subjects and predicates can even be clauses themselves, as in “That Holden
has three mothers isn’t as crazy as it sounds” or “All I know is that the ship was attacked”.
You can see how using recursion to embed clauses inside subjects & predicates can grow sentences a lot.
You can stretch them out almost indefinitely, like, “Fred’s belief that the people who
live on the station that Alex calls home refused to surrender influenced whether the inhabitants
running out of water is as crazy as it sounds” - which kind of makes you do mental calisthenics,
but is a perfectly grammatical English sentence - and probably one that no one’s ever said before.
English offers up a multitude of ways to grow its sentences, and we’ve only really caught a glimpse.
But the addition of complementizer phrases to our theory easily accommodates the kinds
of structures we tend to encounter.
They also help us out with the syntax of questions in English: like, in “Where did the molecule come
from,” we can now see that “where” moves up into the space provided by the CP.
They even suggest new ways of looking at simple sentences; after all, since words like “or”
and “but” normally join together like phrases, the fact that we can hitch ordinary
clauses up to questions, like in “You might solve the case, but will it bring justice”
suggests even the smallest sentences might have a CP stealthily lurking up above.
Expanding beyond English, we can also use this idea to glean insight into common cross-linguistic patterns.
For instance, almost every Germanic language has what’s known as verb-second — or V2 — word order.
That means that in languages like Icelandic or Dutch, no matter how many constituents
in a sentence, and no matter their order, the second one always has to be the tensed verb.
In German, for something like “Peter has read this book,” we get “Peter hat dieses Buch gelesen."
And since German has a freer word order than English, we can also swap the subject and object to
get “Dieses Buch hat Peter gelesen.”
And we can even put the adverb “now” at the front, giving “Jetzt hat Peter dieses Buch gelesen".
And these all work fine, as long as the verb’s second in command. In sentences with multiple
verbs, like “He must have earned money,” almost all of them wind up at the end; but
the leftmost modal “must” is always in the number 2 spot.
So, since we usually think of our sentences as being built up out of rules that make reference
to structure, and not ones that have to count words, how might we use CPs to make sense of all that?
With just a tense phrase, we could suppose that German's mostly like English, but that either the ᴀɢᴇɴᴛ
or the ᴛʜᴇᴍᴇ of the verb can become the subject of the sentence, with the other one staying behind.
So, either “Peter” moves up, or “this book” does.
But it’s harder to explain why an adverb should be able to grab this spot, too; typically,
subjects represent one of the participants in the relationship described by the verb,
not some optional add-on.
With complementizer phrases, another explanation presents itself.
If, instead, tensed verbs always start off grouped with the other verbs at the end of
the clause, and then move up into that C position, it’s easy to see why they always come in
second: with the verb in its place, either the subject, the object, or an adverb, then
snag that front seat.
If all German sentences are CPs, and German CPs are built to always stick verbs into the
second part of the tree, V2 word order comes for free!
German sentences, then, turn out to be a bit like English questions, where the verb always
moves in front of the subject.
The only difference is that on top of the verb, instead of a wh-word like “who”
or “what,” German can move nearly anything there it wants to.
And this becomes the topic of the sentence, like we talked about in our episode on information
structure -- explaining why we find not only subjects and objects there, but adverbs too.
Best of all, this idea makes a specific, testable prediction: if anything can block the verb
from making its way up the tree, V2 order should be impossible.
And sure enough, when the sentence is embedded inside another one, like in “He sees that
Peter has read this book,” all the verbs are shuffled over toward the end.
Since the verb and the complementizer can’t be in the same place at the same time, in
embedded clauses the verb stays put; no more V2!
So whether it’s giving clauses the extra headroom they need to plug into each other,
or capturing the verbal quirks of German syntax, CPs offer us an expansive tool to use in our
exploration of the vast reaches of language.
So, we’ve reached the end of The Ling Space for this week.
If you expanded your understanding of clauses, you learned that the property of recursion
lets us put just about any structure inside itself, including fully formed clauses; that
embedded clauses need a kind of interface between themselves and the next clause up,
in the form of a complementizer phrase; and that these CPs give our theory the added thrust
needed to explain why it is certain languages always put their verb second.
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See you next time! Lukim yu bihain!