So let’s talk about ideas.
When you want to plant a thought in someone else’s head, it’s simple!
Just speak your sentence, and there it is!
And if you need to communicate something a bit more complex, it’s easy enough to wrap
one clause around another and smuggle it in, while your audience is none the wiser.
But just what is a clause, anyway?
How many layers deep can they go, and how do all the different pieces work together
to get the job done?
I’m Moti Lieberman, and this is The Ling Space.
Going all the way back to ancient Greece, people who spent time thinking about language
realized that a sentence like “Ariadne helped the hero navigate the maze” expressed a
complete thought — something that could turn out to be either true or false.
In this way, sentences form a sort of basic linguistic unit.
But the philosopher Aristotle recognized we could also think of sentences as fundamentally binary.
They could always be broken up into a subject, which pointed to the sentence’s topic, and
a predicate, which said something about the subject.
Now, sentences can actually get pretty complex, with multiple subjects and predicates.
But there seems to be something special about the coming together of one subject and predicate
at a time — forming what’s called a clause.
It’s an important idea that’s had a big influence on how we think about the architecture of language.
So let’s dive deep and really take a closer look at what clauses are made of!
We’ll start with a simple sentence, having just one clause, a single subject-predicate pair.
Take “Ariadne helped.”
In the early days of modern linguistics, it had become clear that the subject half of
a simple sentence usually consists of a noun phrase, while its predicate half is more often
than not a verb phrase.
In the 1950s, linguist Noam Chomsky captured this pattern with a rule, which looked like this.
Reading it from left to right, it says that a sentence is composed of one noun phrase
and one verb phrase, in that order.
And while Chomsky wrote out separate rules to cover the contents of both of those phrases,
the same basic insight holds even today.
But we’ve also made plenty of important discoveries since, and we’ve kept on refining
how these rules get spelled out.
So what do they look like today?
And how did we get from there to here?
To get at the answers, let’s start by unraveling the different parts of our sentence a little
more, to see what each half has in common.
In “Ariadne helped,” the subject noun phrase “Ariadne” is made up of just one
noun, while the predicate verb phrase has exactly one verb.
But each of these parts can accommodate much more.
For instance, we could instead say “The Architect helped reluctantly,” where the
noun phrase now has a determiner in it, while the verb phrase includes an adverb.
Noun phrases can also have adjectives in them, like “brave” or “hopeful,” while verb
phrases often contain prepositional phrases, say like “by designing each level.”
Notice that no matter how much we add to each phrase, it still keeps its category.
A noun phrase is a noun phrase, no matter how big it gets, and a verb phrase stays a
verb phrase, regardless of what else you put in there.
What’s essential in each case is that you have a noun in one and a verb in the other.
If those get lost, you’re left with gibberish.
One way to account for this fact is by saying that all phrases have headedness.
That is, every phrase has a head — a single word that makes up the core of its personality.
If you leave it out, the structure collapses.
And this cuts across all categories: noun and verb phrases always have nouns
and verbs in them, adjective and adverb phrases all have at least one adjective or adverb,
and prepositional phrases each begin with a preposition!
Like we talked about back in our episode on it, the theory establishes that each kind
of phrase has to be made up of at least three layers: a head at the bottom, a phrase at
the top that matches its category, and one or more intermediate ‘bar’ levels in between.
This blueprint applied equally to noun phrases, verb phrases, and the rest.
But there was obviously an odd man out; sentences were headless!
And with no intermediate levels to speak of, they seemed to completely break the X-bar mould.
So the question that popped up at the time was: is this an exception to the rule, or
is something missing?
To understand the answer, let’s consider another class of words that can make their
way into the sentence: auxiliary verbs.
Sandwiched between the subject and the predicate in English, we sometimes find modal auxiliaries,
like “can” and “would,” or aspectual auxiliaries, like “have” and “be.”
So, we can just as easily say "Ariadne can help,” or “Ariadne is helping.”
What they all have in common is that these are examples of inflection.
These ‘helping’ verbs don’t carry much meaning by themselves, and they don’t fundamentally
change the overall thrust of the sentence.
Instead, they inflect it, by spelling out certain details — like whether the action
that’s described is necessary or is simply possible, or whether it’s over or still a work in progress.
So, maybe inflection is the crucial ingredient lying at the heart of these sentences.
After all, if we take away these words, we get broken phrases like “Ariadne help”
or “Ariadne helping,” which don’t really work on their own.
But what about sentences without these auxiliary verbs?
If sentences are really headed by inflection, in the same way noun phrases are headed by
nouns, shouldn’t we always be able to see it, no matter what?
Well, it turns out that even simpler sentences like “Ariadne helped” or “Ariadne helps”
have inflection.
In these cases, the verb is either inflected for the past tense, or for agreement with
the third-person singular subject.
It might seem weird to think about a suffix on the end of the verb as being the head of the sentence,
but we have some good reasons to think this is right.
For one, a sentence’s tense can actually move independently of the main verb.
In English, when we want to ask a certain kind of question, we move the auxiliary verb
over to the front, as in “Will Robert wake up?”
When there is no auxiliary, we don’t move the main verb; we only move the tense.
We attach it to a kind of meaningless dummy verb to give it a way to get around.
So, “Robert woke up” doesn’t become “Woke Robert up?”
Instead, it turns into “Did Robert wake up?”
The past tense is all the way at the front of the sentence, totally disconnected from the verb.
Inflection can also live on its own in declarative sentences, like when negation blocks it from
keeping in touch with the verb it’s normally attached to.
In “Saito does not want to be filled with regret,” the tense and agreement information
show up on “do” instead of “want.”
And it can also get left behind when the verb disappears altogether.
In the sentence “Mal likes to dream — and Cobb does too,” we understand that the
second part means “Cobb likes to dream too.”
The entire verb phrase has been erased, but the inflectional information stayed behind.
So sentences look like they’re in a one-to-one relationship with inflection, meaning that
they’re really inflectional phrases, or IPs.
Our updated picture of a clause now looks like this, where that “inflection” part
of the tree can either contain an auxiliary verb, or just some specification about the
tense and agreement that eventually appear on the verb.
Clauses now have the same three-layered structure as every other phrase.
They fit nicely into our theory, and we’re able to account for more data than
before, which is always a good thing!
Now, since these discoveries were made, we've continued to update the system.
For example, in the 1980s, it was determined that there must be even more structure than
we’ve seen so far.
To see why, let’s look at French.
Even though tensed verbs are always found before adverbs and negation, as in “Elle
rêve souvent” or “Il ne rêve pas,” tenseless verbs aren’t.
In fact, when you try to put them before negation, you get pretty bad results.
The sentence “N’oublier pas son nom, ce n’est pas un exploit” — translating
as “To forget not one’s name isn’t worth writing home about” — sounds about as
weird in French as it does in English.
But tenseless verbs can still show up before adverbs, as in "Lire attentivement ce texte
vous préparera pour l’examen.”
So it looks like there must be a position in the clause above negation, where verbs
go to get tense.
But it also looks like there’s another spot, just below negation and just above the adverb,
a kind of inflectional limbo, where tenseless verbs wind up when they can’t climb any higher.
So, you have sentences like “Ne pas arriver souvent en retard, c’est triste,” where
the verb "arriver" gets stuck in between.
Because “arriver” can lie comfortably after “pas” and before “souvent,”
our clause structure must look something like this.
Information about tense sits at the top, while another, separate position for tenseless verbs
hangs lower down — possibly related to verbal agreement.
So, we’ve had to ‘explode’ the inflectional phrase into different parts.
Clauses are actually tense phrases, or TPs.
And this makes intuitive sense, because sentences can’t stand on their own without tense.
Now, as much as our understanding has improved over the years, we still don’t understand everything.
And plus, clauses come in all kinds of shapes and sizes!
They can join together, like in “Robert was revived, and then he opened the safe.”
Or you can stick one right after a verb or noun, like in “Cobb said they were waiting
for a train,” or “Mal’s belief that the world was a dream worried her.”
They can even go on to be subjects and predicates themselves!
The variations seem limitless, and we’ve really only scratched the surface.
So, you can be sure we’ll come back to talk about them more in the future.
But for now, it’s safe to say that with everything we’ve discovered about clauses,
from subjects and predicates to inflection and tense, there’s definitely more going
on with this idea than we first thought!
So, we’ve reached the end of The Ling Space for this week.
If you exploded your inflectional phrases, you learned that simple sentences contain
a single subject and predicate pair, otherwise known as a clause; that sentences always have
some inflection, in the form of either an auxiliary or a suffix on the verb; that thinking
about sentences as inflectional phrases helps them fit into our theory, explaining some
lingering mysteries along the way; and that we can break inflectional phrases down further,
making tense the phrase for the sentence.
The Ling Space is produced by me, Moti Lieberman, and directed by Adèle-Elise Prévost.
This week’s episode was written by Stephan Hurtubise.
Our editor is Georges Coulombe, our music is by Shane Turner, and our graphics team is atelierMUSE.
We’re down in the comments below, or you can bring the discussion back over to our
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And we’ll see you in two weeks. Totazkeh!