Relative clauses

Intuition [Beginner]

A relative clause is a dependent clause that describes a noun. It gives you extra information about which person, thing, or place you are talking about.

There are two kinds:

1. Defining (restrictive) relative clause: Identifies which noun we mean. The sentence would be incomplete or unclear without it.

   • "The student who scored the highest won a scholarship."
   • Without the relative clause, "The student won a scholarship" is vague -- which student?

2. Non-defining (non-restrictive) relative clause: Adds extra information that is nice to know but not essential. The sentence makes sense without it.

   • "My sister**, who lives in Paris,** is visiting next week."
   • Without the relative clause, "My sister is visiting next week" is perfectly clear -- the Paris detail is bonus information.

Relative clauses are introduced by relative pronouns:

Pronoun	Used for
who	people (subject)
whom	people (object)
whose	possession (people or things)
which	things
that	people or things (defining clauses only)

Visual [Beginner]

DEFINING relative clause (no commas):

  The book   [that I read]   was excellent.
  -------    -------------   -------
  noun       relative         main clause
             clause           continues
             (identifies
              WHICH book)

NON-DEFINING relative clause (commas around it):

  The Eiffel Tower,  [which was built in 1889],  is iconic.
  ---------------    ------------------------    ---------
  noun               relative clause              main clause
                     (extra info, already          continues
                      clear WHICH tower)

When can you OMIT the relative pronoun?

  Object position in a DEFINING clause:
    "The book (that) I read was excellent."     -- OK to omit
    "The person (whom) I called was busy."      -- OK to omit

  Subject position -- NEVER omit:
    "The person who called me was busy."        -- "who" is required
    "The book that is on the table is mine."    -- "that" is required

  Non-defining clauses -- NEVER omit:
    "Paris, which I love, is beautiful."        -- "which" is required

Worked example [Beginner]

Identify and analyze the relative clause in each sentence.

1. "The car that she bought is red."

• Relative clause: "that she bought"
• Type: defining (no commas -- we need this to know which car).
• Relative pronoun: "that" (refers to "the car," acts as object of "bought").
• The pronoun can be omitted: "The car she bought is red."

2. "My father, who is a doctor, works long hours."

• Relative clause: "who is a doctor"
• Type: non-defining (set off by commas -- we already know who "my father" is).
• Relative pronoun: "who" (refers to "my father," acts as subject).
• The pronoun CANNOT be omitted (subject position, and it is non-defining).

3. "The author whose book I read is giving a talk."

• Relative clause: "whose book I read"
• Type: defining (tells us which author).
• Relative pronoun: "whose" (indicates possession -- the book belongs to the author).

Check your understanding [Beginner]

Formal definition [Intermediate+]

A relative clause is a postnominal dependent clause that modifies a head noun. It contains a gap (or a resumptive pronoun) that is co-indexed with the head noun, which serves as its antecedent.

Formal structure:

[NP ... [N head noun] ... [CP [C rel pronoun] ... gap ... ]]

The relative pronoun has a dual function: it serves as the complementizer/relativizer introducing the clause, and it bears a grammatical role (subject, object, possessive, oblique) inside the relative clause.

Defining vs. non-defining:

Property	Defining (restrictive)	Non-defining (non-restrictive)
Function	Restricts the reference of the head noun	Adds supplementary information
Punctuation	No commas	Set off by commas
Relative pronouns	who, whom, whose, which, that	who, whom, whose, which (not that)
Pronoun omission	Possible in object position	Not possible
Entailment	"The students who passed celebrated" does not entail all students passed	"My brother, who lives in Tokyo, is visiting" entails my brother lives in Tokyo

Relative pronoun selection by grammatical role:

Role in relative clause	Pronoun	Example
Subject	who / that / which	the person who called
Direct object	whom / who / that / zero	the person (whom) I saw
Indirect object	whom / who / that / zero	the person (whom) I gave the book
Oblique (object of preposition)	whom / who / which / that / zero	the person to whom I spoke
Possessive	whose	the person whose car was stolen

Key concepts [Intermediate+]

1. That vs. which. In defining clauses, both that and which can refer to things ("the book that/which I read"). Many style guides (particularly American) recommend that for defining clauses and which for non-defining clauses, but this is a prescriptive convention, not a grammatical rule. In non-defining clauses, that is genuinely ungrammatical.

2. Pied-piping vs. preposition stranding. When the relative pronoun is the object of a preposition, the preposition can appear before the pronoun (pied-piping) or at the end of the clause (stranding): "the person to whom I spoke" (formal, pied-piped) vs. "the person (who) I spoke to" (informal, stranded). Preposition stranding is characteristic of English and a few other Germanic languages; it is rare cross-linguistically.

3. Relative clauses with whose. Whose indicates possession and can modify both animate and inanimate head nouns: "the author whose book I read" (animate) and "the company whose profits increased" (inanimate). Some prescriptive guides restrict whose to animates, recommending of which for things, but this restriction is not observed in standard usage.

4. Sentential relative clauses. Which can also refer to an entire preceding clause rather than a single noun: "She arrived late, which annoyed everyone." Here which has a clause as its antecedent, not an NP. This construction is always non-defining.

5. Stacked relative clauses. Multiple relative clauses can modify the same head noun: "the book [that I read] [that changed my perspective]." Stacked relatives are always defining and are processed incrementally, which can create processing difficulty with three or more stacked clauses.

Linguistic theory [Master]

The syntax of relative clauses has been one of the most extensively debated topics in generative grammar. Two main families of analysis exist:

The raising analysis (Vergnaud 1974; Kayne 1994; Bhatt 2002): The relative pronoun (or the head noun itself) originates inside the relative clause and moves to the left edge. Under the matching analysis (Chomsky 1965; Sauerland 1998), an internal head is matched with (and deleted in favor of) the external head. Under the head-raising analysis (Vergnaud 1974; Kayne 1994), the head noun literally moves from its base position inside the relative clause to the head position outside it.

Evidence for the raising analysis includes connectivity effects: binding and scope relations inside the relative clause behave as if the head noun were in its base position. "The picture of himself that John likes" allows himself to be bound by John, suggesting that "the picture of himself" was originally the object of likes and underwent raising.

The adjunct analysis (Chomsky 1977; Safir 1986): The relative clause is adjoined to the head noun (as an NP adjunct) or to a projection containing the head noun (as a CP adjunct). Under this view, the head noun is base-generated in its surface position and is not moved from inside the relative clause.

de Vries (2002) proposes a unified analysis in which all relative clauses involve a determiner phrase containing a relative CP, with the head noun generated either inside or outside the CP depending on construction type.

Cross-linguistic typology (Keenan & Comrie 1977): Languages differ in which grammatical roles can be relativized. The Accessibility Hierarchy predicts that if a language can relativize role N, it can relativize all roles higher on the hierarchy:

Subject > Direct Object > Indirect Object > Oblique > Genitive > Object of Comparison

English can relativize all positions on the hierarchy (using that, zero, or who/whom/whose). Many languages can only relativize subjects, or subjects and direct objects.

That-trace effects in relatives: In standard English, the relative pronoun that cannot be used when it is followed by a trace in subject position: "Who is the person that __ left?" is degraded compared to "*Who is the person who __ left? This parallels the that-trace effect in complement clauses and is attributed to the same Empty Category Principle (ECP) constraint.

** island constraints** also apply to relative clauses. Extraction out of a relative clause is severely restricted: "*Which book do you know the person [who wrote __]?" is ungrammatical because the relative clause is a complex NP island (Ross 1967). This is one of the strongest island effects in English.

Historical context [Master]

Old English had a rich system of relative clauses using inflected relative pronouns (se, seo, thæt) that agreed with the antecedent in gender, number, and case. The uninflected particle the (ancestor of that) was also used as a relativizer.

During Middle English, the loss of case inflection on the demonstrative/relative pronouns led to ambiguity. That became the default relativizer, and which (originally an interrogative pronoun) was recruited as a relative pronoun for inanimates. Who/whom (also originally interrogative) was pressed into service as a relative pronoun for humans during the 15th-16th centuries, partly under the influence of Latin relative clauses.

The prescriptive rule restricting that to defining clauses and which to non-defining clauses has no basis in the history of English or in the grammar of most speakers. It was promoted by H.W. Fowler in The King's English (1906) and A Dictionary of Modern English Usage (1926) and was taken up by American style guides, but British English continues to use which freely in defining clauses.

The omission of the relative pronoun (the "zero relative") is a distinctly English phenomenon, rare in other Germanic languages. It became common in Middle English and is now fully standard in defining clauses when the pronoun is in object position.

Bibliography [Master]

• Bhatt, R. (2002). The raising analysis of relative clauses: Evidence from adjectival modification. Natural Language Semantics, 10(1), 43-90.
• Chomsky, N. (1977). On wh-movement. In P. Culicover, T. Wasow, & A. Akmajian (Eds.), Formal Syntax. Academic Press.
• de Vries, M. (2002). The Syntax of Relativization. LOT.
• Huddleston, R., & Pullum, G. (2002). The Cambridge Grammar of the English Language. Cambridge University Press.
• Kayne, R. (1994). The Antisymmetry of Syntax. MIT Press.
• Keenan, E., & Comrie, B. (1977). Noun phrase accessibility and universal grammar. Linguistic Inquiry, 8(1), 63-99.
• Ross, J. (1967). Constraints on Variables in Syntax. PhD dissertation, MIT.
• Sauerland, U. (1998). The meaning of chains. PhD dissertation, MIT.
• Vergnaud, J.-R. (1974). French relative clauses. PhD dissertation, MIT.