Read the following four examples out-loud:
- Who did John say that Mary likes?
- Who did John say Mary likes?
- Who did John say that likes Mary?
- Who did John say likes Mary?
My guess is that (3) sounds odd when compared to the rest. However, we can’t just say that (3) doesn’t “mean” anything. We must be sure to separate a sentence’s form from its meaning. Noam Chomsky’s (in)famous example: colorless green ideas sleep furiously demonstrates that an utterance can be utterly without meaning, yet still have grammatical form. Since we’ve ruled out meaning, the problem with (3) must be its form.
Explaining what’s wrong with (3)’s form is the kind of puzzle tackled in modern syntax. Many answers are often highly abstract in nature, causing those outside the field to question the legitimacy of linguistics. A frequent criticism is that abstract models are not truly representative of the way we think about, or use, language. I agree with this claim, but it misses the point that we aren’t looking for a theory of performance; we are looking for a theory of competence. The true task is to understand the fundamental system underlying knowledge (and use) of language. Not surprisingly, it turns out this system is quite complex and abstraction helps to manage the complexity.
If we turn our attention back to the examples above, two things jump out. First, notice that “who” is an object in (1) and (2), but a subject in (3) and (4). But what exactly are subjects and objects? Roughly speaking, the termssubject and object denote syntactic functions that a word or phrase may have. For instance, you might think that subjects are limited to nouns; after all, it seems reasonable to think that subject is just an important role that a noun (e.g. person, place, or (abstract) thing) has in a sentence. However, a little creativity shows that a fullclause may in fact be the subject of a sentence:
- That John applied to law school is surprising.
In example (5), the subject is the entire clause: “That John applied to law school”. Clearly a clause is not a noun, and in many important respects, it resembles an entire sentence*. Again, it is easy to wonder why this matters at all. For one thing, regardless of whatever definition we come up with for “noun” or “clause”, we recognize that either may serve the function subject. This is important because linguists and philosophers of language have long sought answers which explain how knowledge and use of language relate to the world. If sentences are one way of talking about and investigating the world, then clearly subjects are a central part of this exploration. We might not know much right now, but we do know that clauses and nouns may serve as subjects, and this helps us better understand how language is tied to the world. How about objects?
Like subject, object is a separate functional role within a sentence. In a technical sense, these functions are represented by specific structural relations between phrases in a syntactic tree, or between sets in set-theoretic terminology. It is important to understand that no word or phrase is inherently subject or object; these roles are like masks that words or phrases may put on when they enter a sentence.
Moving forward, it looks like subject + that = bad, while object + that = good.
In other words, objects are indifferent to the presence of “that”, whereas subjects are sensitive to its presence. This is a revealing state of affairs. It shows that subjects and objects have different syntactic behavior, in addition to the semantic differences they adopt by taking on their respective functional roles.
So what? Why is it interesting that subjects and objects have different syntactic behavior? Well, think about the possibility that syntax is essentially a structure (or a set of structures) in the brain. This claim is by no means obvious, but it is one of the more revolutionary paradigm shifts of 20th century science. First proposed and developed by Chomsky in the 1950s, this “innateness” hypothesis has led to revolutions not just in linguistics, but cognitive science generally. As such, an asymmetry in syntax can be viewed as an asymmetry in a structure of the brain, clearly a fascinating conclusion.
Working under the assumption that all humans possess a Universal Grammar, linguists have set out to rigorously categorize and describe languages across the world. With this universalism in mind, linguists typically draw on data from a wide variety of unrelated languages in order to show their abstract similarities. Just as chemists understand that liquid water and ice are both fundamentally H2O, linguists attempt to show that English and Japanese are also the same, albeit at a “molecular” level. Current research is as exciting as it is unpredictable, especially given the rapid changes in the field following the publication of Chomsky’s Minimalist Program in 1995. What does appear to be clear, however, is that like the human genome, the language faculty is essentially the same across our species.
* All sentences are clauses, but not all clauses are sentences; hence, the set of sentences is a proper subset of the set of clauses.