Conditional Clause in Grammar

Glossary of Grammatical and Rhetorical Terms

Conditional clauses
The first stanza of Rudyard Kipling's "If—" (1895), a poem made up of series of conditional clauses. Getty Images

In English grammar, a conditional clause is a type of adverbial clause that states a hypothesis or condition, real (factual) or imagined (counterfactual). A sentence containing one or more conditional clauses and a main clause (which expresses the result of the condition) is called a conditional sentence (also known as a conditional construction).

A conditional clause is most often introduced by the subordinating conjunction if. Other conditional subordinators include unless, even if, provided that, on condition that, as long as, and in the case of. (Note that unless functions as a negative subordinator.)

Conditional clauses tend to come at the beginning of complex sentences, but (like other adverbial clauses) they may also come at the end. 

Examples and Observations

  • " If we had no winter, the spring would not be so pleasant; if we did not sometimes taste of adversity, prosperity would not be so welcome." (Anne Bradstreet, "Meditations Divine and Moral")
  • "Romans park their cars the way I would park if I had just spilled a beaker of hydrochloric acid on my lap." (Bill Bryson, Neither Here Nor There: Travels in Europe. William Morrow, 1992)
  • "Even if it snows, even if there is a tornado, nothing will put off this expedition." (J.F. Powers, "Death of a Favorite," 1951)
  • "After that first taste of the sandal in the dining room, I foolishly believed I would be safe as long as I stayed away from the table." (Adrienne Kress, Alex and the Ironic Gentleman. Weinstein Books, 2007)

What Are 'Conditions'?

"Conditions deal with imagined situations: some are possible, some are unlikely, some are impossible. The speaker/writer imagines that something can or cannot happen or have happened, and then compares that situation with possible consequences or outcomes, or offers further logical conclusions about the situation." (R. Carter, Cambridge Grammar of English. Cambridge University Press, 2006)

Stylistic Advice: Positioning Conditional Clauses

"Conditional clauses have traditionally been placed at the beginning of a sentence, but you should feel free to place a conditional clause elsewhere if doing so would make the provision easier to read. The longer the conditional clause, the more likely it is that the provision would be more readable with the matrix clause rather than the conditional clause at the front of the sentence. If both the conditional clause and the matrix clause contain more than one element, you would likely be better off expressing them as two sentences." (Kenneth A. Adams, A Manual of Style for Contract Drafting. American Bar Association, 2004)

Types of Conditional Clauses

There are six main types of conditional sentence:

  1. For example, the equilibrium between liquid and vapor is upset if the temperature is increased.
    (General rule, or law of nature: it always happens.)
  2. If you start thinking about this game, it will drive you crazy.
    (Open future condition: it may or may not happen.)
  3. But if you really wanted to be on Malibu Beach, you'd be there.
    (Unlikely future condition: it probably won't happen.)
  4. If I were you, I would go to the conference center itself and ask to see someone in security.
    (Impossible future condition: it could never happen.)
  5. "I would have resigned if they had made the decision themselves," she said.
    (Impossible past condition: it didn't happen.)
  6. If he had been working for three days and three nights then it was in the suit he was wearing now.
    (Unknown past condition: we don't know the facts.)

(John Seely, Grammar for Teachers. Oxpecker, 2007)