Conjunctions

Intuition [Beginner]

A conjunction is a word that joins other words, phrases, or clauses together. Think of conjunctions as the glue of a sentence. "Bread and butter." "I was tired but I kept working." "She stayed home because it was raining."

There are three main kinds. Coordinating conjunctions join equal parts: and, but, or, nor, for, so, yet. You can remember them with the acronym FANBOYS (for, and, nor, but, or, yet, so). "Tea or coffee?" Both "tea" and "coffee" are equal nouns joined by "or."

Subordinating conjunctions join a dependent clause to a main clause: because, although, if, when, while, since, unless, before, after. "I stayed inside because it was raining." "Because it was raining" is the dependent clause, and "because" is the subordinating conjunction that attaches it.

Correlative conjunctions come in pairs: either/or, neither/nor, not only/but also, both/and. "You can have either tea or coffee." Both parts work together to connect the options.

Visual [Beginner]

Coordinating (FANBOYS)      Subordinating             Correlative (pairs)
  F - for                     because                   both/and
  A - and                     although                  either/or
  N - nor                     if                        neither/nor
  B - but                     when                      not only/but also
  O - or                      while                     whether/or
  Y - yet                     since
  S - so                      unless
                               before, after

Each type joins things differently: equals, dependent to main, or in pairs.

Worked example [Beginner]

Identify the conjunctions and what they join: "The dog barked and the cat ran away, but they both came back when I called."

• and -- joins "the dog barked" and "the cat ran away" (two equal clauses)
• but -- joins the first part with "they both came back" (two equal clauses with contrast)
• when -- subordinating conjunction; "when I called" is a dependent clause attached to "they both came back"

"And" and "but" are coordinating. "When" is subordinating.

Check your understanding [Beginner]

Formal definition [Intermediate+]

A conjunction is a word (or pair of words) that links two or more syntactic constituents, establishing a relationship of coordination, subordination, or correlation between them.

Coordinating conjunctions

The seven coordinating conjunctions (FANBOYS): for, and, nor, but, or, yet, so.

They join constituents of the same syntactic type (NP with NP, clause with clause, adjective with adjective):

• NP + NP: "cats and dogs"
• VP + VP: "walked but did not run"
• AdjP + AdjP: "tall yet gentle"
• Clause + Clause: "It rained, so we went inside."

Constraints on coordination: standard coordination requires like with like. "She sang beautifully and a song" is ungrammatical because an adverb phrase and an NP are not the same type. However, there are systematic exceptions where non-parallel structures coordinate under certain discourse conditions.

Subordinating conjunctions

Subordinating conjunctions introduce a dependent clause and mark its semantic relation to the main clause:

Relation	Subordinating conjunctions	Example
Cause/reason	because, since, as	"I left because it was late."
Concession	although, though, even though, whereas	"Although tired, she continued."
Condition	if, unless, provided that, assuming	"If it rains, we will cancel."
Time	when, while, before, after, until, once, as	"Call me when you arrive."
Purpose	so that, in order that	"She studied so that she would pass."
Result	so ... that, such ... that	"It was so cold that the pipes froze."
Manner	as, as if, as though	"He acted as if nothing happened."
Place	where, wherever	"Stay where I can see you."

Correlative conjunctions

Correlative conjunctions are two-part connectors that work as a unit:

• both ... and: "Both the manager and the employees agreed."
• either ... or: "You can either stay or leave."
• neither ... nor: "Neither John nor Mary was informed."
• not only ... but also: "She not only wrote the report but also presented it."
• whether ... or: "I do not know whether to stay or go."

Correlatives enforce parallelism: each part of the pair must be followed by the same syntactic type. "She not only wrote the report but also it was presented by her" breaks parallelism (VP + clause) and is ungrammatical in formal writing.

Conjunctions vs. other connectives

• Conjunctive adverbs (however, therefore, moreover, nevertheless) are adverbs, not conjunctions. They connect independent sentences but require a semicolon or period: "It was late; however, we continued." Using a comma creates a comma splice.
• Prepositions with clause complements (before, after, since) can function as either prepositions or subordinating conjunctions, depending on whether they take an NP or a clause.

Linguistic theory [Master]

Coordination as a syntactic operation

Coordination has been a persistent puzzle for syntactic theory. The core problem: what is the structure of a coordinated phrase? Three main analyses have been proposed:

1. Conjunction as a head (Johannessen 1998): The conjunction is the head of a coordination phrase (CoP), and the conjuncts are its complements. "Cats and dogs" has the structure [CoP cats [Co' [Co and] dogs]]. This predicts that conjunctions select their conjuncts and can impose categorial restrictions.

2. Conjunction as a coordinator with a flat structure: The coordinated phrase inherits its category from the conjuncts. [NP cats and dogs] is an NP because both conjuncts are NPs. This is the simplest analysis but struggles with asymmetric coordination.

3. Multidominance: Both conjuncts are dominated by the same mother node without an intervening CoP. "Cats" and "dogs" are both direct daughters of the NP. This avoids extra structure but requires allowing a single node to have multiple mothers.

The coordinate structure constraint

Ross (1967) identified the Coordinate Structure Constraint (CSC): no element may be extracted from a single conjunct in a coordinate structure. "What did you buy books and?" is ungrammatical because "what" is extracted from only the second conjunct. This constraint applies across languages and is considered a syntactic island. The CSC is one of the strongest arguments that coordination creates a unified syntactic constituent, not merely a linear sequence.

Subordination and clause combining

Subordinating conjunctions mark the boundary between main and dependent clauses. In functional-typological work (Matthiessen & Thompson 1988), clause combining is viewed as a continuum from coordination (equal status) through various degrees of subordination (complement clauses, adverbial clauses, relative clauses) to nominalization (clauses turned into noun phrases). Subordinating conjunctions occupy the middle of this continuum.

Cross-linguistically, the set of subordinating conjunction meanings is remarkably stable: cause, condition, concession, time, purpose, and manner appear in virtually every language, though the formal markers differ. Haspelmath (2007) shows that coordinating conjunction meanings (and, or, but) are also near-universal, though the boundary between coordination and subordination is not always sharp.

Connections

Conjunctions have direct analogues in formal logic. "And" corresponds to logical conjunction ($\wedge$), "or" to disjunction ($\vee$), "not" to negation ($\neg$), and "if...then" to material implication ($\to$). But the mapping is not one-to-one: natural language "or" can be inclusive or exclusive ("tea or coffee" typically means exclusive-or, while "skill or effort" is inclusive), while logical $\vee$ is always inclusive. De Morgan's laws in logic -- $\neg (P\wedge Q)\equiv \neg P\vee \neg Q$ -- explain why "neither/nor" and "not either/or" are equivalent. The parallelism constraints on correlative conjunctions mirror the type-matching requirements in typed lambda calculus: both branches of a conjunction must return the same type.

Historical context [Master]

The term "conjunction" comes from Latin coniunctio ("a joining together"), from con- ("together") + iungere ("to join"). Roman grammarians recognized conjunctions as a distinct word class, though they grouped them with interjections as "minor" parts of speech.

In Old English, coordinating conjunctions were limited: and (and), ac (but), o**e (or). The full FANBOYS set emerged over centuries. "For" as a conjunction developed from the preposition for in Middle English. "So" as a conjunction ("so I left") emerged from the adverbial use. "Yet" as a conjunction is a Middle English development from Old English git ("still, yet"). "Nor" is a compound of "not" + "or" that became a single conjunction.

Subordinating conjunctions in Old English were often expressed with case-marked particles and word order rather than dedicated words. As case markings eroded, subordinating conjunctions proliferated. "Because" derives from the phrase "by cause" (Middle English), which was originally a prepositional phrase ("by cause of") before developing a clausal complement. "Although" is a compound of "all" + "though" (literally "completely though"). "Unless" comes from "on less than" (Old French moins que calqued into English), meaning "under a lesser condition than."

Bibliography [Master]

• Haspelmath, M. (2007). "Coordination." In T. Shopen (Ed.), Language Typology and Syntactic Description, Vol. 2. Cambridge University Press.
• Johannessen, J. B. (1998). Coordination. Oxford University Press.
• Ross, J. R. (1967). Constraints on Variables in Syntax. PhD dissertation, MIT.
• Culicover, P. W. (1999). Syntactic Nuts: Hard Cases, Syntactic Theory, and Language Acquisition. Oxford University Press.
• Matthiessen, C. & Thompson, S. A. (1988). "The Structure of Discourse and 'Subordination'." In J. Haiman & S. A. Thompson (Eds.), Clause Combining in Grammar and Discourse. John Benjamins.