Field of Science

What makes a sentence ungrammatical?

This is the latest in a series of posts explaining the scientific motivations for the VerbCorner project.

There are many sentences that are grammatical but don't make much sense, including Chomsky's famous “colorless green ideas sleep furiously,” and sentences which seemed perfectly interpretable but are grammatical, such as “John fell the vase” or “Sally laughed Mary” (where the first sentence means that John caused the vase to fall, and the second sentence means that Sally made Mary laugh). You can hit at a window or kick at a window but not shatter at a window or break at a window (unless you are the one shattering or breaking!).

Sentence frames

Notice that these are not agreement errors (“Sally laughed”) or other word-ending errors ("Sally runned to the store"), but instead have something to do with the structure of the sentence as a whole. Linguists often refer to these sentence structures as "frames". There is the transitive frame (NOUN VERB NOUN), the intransitive frame (NOUN VERB), the 'at' frame (NOUN VERB at NOUN), etc. And it seems that certain verbs can go in some frames but not others.

There are many sentence frames (there is disagreement about exactly how to count them, but there are at least a few dozen), and most verbs can appear in somewhere around a half dozen of them. For instance, "thump" can appear in at least eight frames:

NOUN VERB NOUN:                                                  John thumped the door.
NOUN VERB NOUN with NOUN:                             John thumped the door with a stick.
NOUN VERB NOUNs together:                                   John thumped the sticks together.
NOUN VERB NOUN ADJECTIVE:                           John thumped the door open.
NOUN VERB NOUN ADJECTIVE with NOUN:       John thumped the door open with a stick.
NOUN VERB NOUN to [STATE]:                              John thumped the door to pieces.
NOUN VERB NOUN to [STATE] with NOUN:         John thumped the door to pieces with a stick.
NOUN VERB NOUN against NOUN:                         John thumped the stick against the door.

But there are a large number of frames "thump" can't appear in (at least, not without a lot of straining), such as:

NOUN VERB NOUN that SENTENCE:                    John thumped that Mary was angry.
NOUN VERB NOUN NOUN:                                    John thumped Mary the book.
NOUN VERB easily:                                                   Books thump easily.
There VERB NOUN out of [LOCATION]:               There thumped John out of the house.
NOUN VERB what INFINITIVE:                             John thumped what to do.
NOUN VERB INFINITIVE:                                      John thumped to sing

Explaining language

Perhaps these are just funny facts that we must learn about the language we speak, with no rhyme or reason. This is probably true for some aspects of grammar, like which verbs are irregular (that the past tense of “sleep” is “slept” is a historical accident). But a lot of researchers have suspected that there is a reason why language is the way it is and why certain verbs can go into certain frames but not others.

Going back several decades, researchers noticed that when you sort sentences based on the kind of sentence frames they can fit into, you do not get incoherent jumbles of verbs, but rather groups of verbs that all seem to share something in common. So “shatter” and “break” can be used with the object that is shattering or breaking as the direct object ("John shattered/broke the vase") or as the subject ("The vase shattered/broke"). All the verbs that can do this seem to describe some caused change of state (the vase is changing). Verbs that do not describe some kind of caused change cannot appear in both of these forms (you can say “John hit/kicked the vase" but not "The vase hit/kicked" -- at least not without a very special vase!).

Causality might also explain why you can hit at a window or kick at a window but not shatter or break at a window: the addition of the preposition "at" suggests that the action was ineffectual (you tried hitting the window without doing much damage) which is simply nonsensical with words that by their very definition require success. How do you ineffectually shatter a window? You either shatter it or you don't.

So maybe which verbs can go in which frames is not so mysterious after all. Maybe it is a simple function of meaning. Certain verbs have the right meanings for certain sentence frames. No more explanation necessary.

The VerbCorner Contribution

When you group verbs based on the frames they can appear in, you get several hundred groups of verbs in English. Of these, only a handful have been studied in any detail. While it does look like those groups can be explained in terms of their meaning, you might wonder if perhaps these are unusual cases, and if researchers looked at the rest, we would find something different. In fact, a number of researchers have wondered just that.

The difficulty has always been that there are a lot of verbs and a lot of groups. Studying just one group can take a research team years. Studying all of them would take lifetimes.

This is why we decided to crowd-source the problem. Rather than have a few people spend a lifetime, if a lots of people each contribute just a little, we can finish the project in a couple years, if not sooner.

Contribute to the VerbCorner project at


RM said...

I don't think the "at the window" bit is due to causality. Rather, I think it's more due to the directional nature of the action. Kicking or hitting can be directed, whereas shattering or breaking is undirected. "John sat at the window" (with the "at" meaning the same as "hit at" or "kicked at") doesn't make any sense - but not because sitting can't be ineffectual. Rather, it's nonsensical because sitting has an obligate direction (down) and as such you cannot sit in the direction of an arbitrary object. Likewise, shattering can't take an associated direction, thus shattering toward an object is nonsensical.

Also, while "John shot at the target" might imply ineffectualness, "John shot at the target and hit a bullseye" certainly does not. NOUN VERB at NOUN doesn't require ineffectualness, it's simply "damning with faint praise", as we typically use more precise constructs when the meaning is "VERBED at and succeeded".

GamesWithWords said...

RM: You could be right. It does seem like directionality is what the 'at' is doing in "John shouted at Mary". But what do you make of:

"John didn't really hit the vase. He mostly hit at the vase."

Regardless, this is why the VerbCorner project is important. We can argue about what the semantics of these sentences is and come up with examples and counter-examples, but nothing beats a systematic survey.