Conditional Sentence

What Is a Conditional Sentence?

A conditional sentence is a sentence that includes a condition (e.g., If it snows) and the outcome of the condition occurring (e.g., the game will be cancelled). In each of these examples, the clause expressing the condition is highlighted:

• If you snooze, you lose.
• If you study tonight, you will pass your exam tomorrow.
• If you were smarter, you would know what you don't know.
• If we had read the map, we would have avoided the river.

The 4 Types of Conditional Sentence

Here are the four types of conditional sentence with an explanation of each type:

Type	Function	Example
zero conditional	Expresses something as a fact	If you sleep, you dream.
first conditional	States the result of a possible future event occurring	If you get some sleep, you will feel better.
second conditional	States the result of an unlikely event occurring or an untruth being true	If you became an insomniac, you would understand. (unlikely event occurring) If you were an insomniac, you would understand. (untruth being true)
third conditional	States how the situation would be different with a different past	If you had slept last night, you would have beaten your record.

Zero Conditional Sentences

A zero-conditional sentence expresses a general fact (i.e., a situation where one thing always causes another).

• If you rest, you rust. (Actress Helen Hayes)
• If you think you can, you can. And if you think you can't, you are right. (Business magnate Henry Ford)
• You do ill if you praise, but you do worse if you censure, what you do not understand. (Polymath Leonardo da Vinci)

Structure: With a zero-conditional sentence, the simple present tense is used in both clauses. Also, the words if and when are interchangeable.

• If I make money, I'm happy. When I lose money, I'm happy. (Gambling magnate Lui Che Woo)
(With a zero-conditional sentence, the message is expressed as a fact. That doesn't mean it's true of course.)

First Conditional Sentences

A first-conditional sentence states the result of a hypothetical, but possible, future event (e.g., If you rest) occurring.

• If one swain [young lover] scorns you, you will soon find another. (Roman poet Virgil)
• If I like a food, even if it's bad for me, I will eat it. (Reality TV star Kim Kardashian)

Structure: With a first-conditional sentence, the simple present tense is used in the if-clause, and the simple future tense used in the main clause.

Second Conditional Sentences

A second-conditional sentence states the result of an unlikely event occurring (e.g., If the boat sank) or an untruth being truth (e.g., If they were on time).

• If I won the lottery, I would still love you. I'd miss you, but I'd still love you. (Comedian Frank Carson)
• If I saw a heat wave, I would wave back. (Comedian Steven Wright)
• If I had any humility, I would be perfect. (Media mogul Ted Turner)
• If you set out to be liked, you would compromise on everything and achieve nothing. (Margaret Thatcher)

Structure: With a second-conditional sentence, the simple past tense is used in the if-clause, and would (rarely should or could) with the base form of a verb is used in the main clause.

Nowadays, it's safe to say that the simple past tense is used in the if-clause, but in fact it's the past subjunctive, which is identical to the simple past tense apart from when I and he/she/it are used with the verb to be (e.g., If I were millionaire, If she were to try). (There's an entry on the subjunctive mood.)

• If I were a rich man, all day long I'd biddy-biddy-bum. (Extract from "Fiddler on the Roof")
(I'd is short for I would. To biddy-biddy-bum must be a verb.)
• Life would be tragic if it weren't funny. (Theoretical physicist Stephen Hawking)

That said, it is now common to see the simple past tense used in all circumstances.

• If I was a man, I don't know whether I'd settle down long before I was 50. (Journalist Mariella Frostrup)

Third Conditional Sentences

Third-conditional sentences express how the situation would be different if the past had been different.

• If my lawyer and I had communicated properly in January 1958, this whole history would have been entirely different. (Inventor of the laser Gordon Gould, who fought unsuccessfully to patent it)
• If I had learned education, I would not have had time to learn anything else. (Business magnate Cornelius Vanderbilt)
• If I had known how hard it would be to do something new in the payments industry, I would never have started PayPal. (Co-founder of PayPal Peter Thiel)

With a third-conditional sentence, the past perfect tense is used in the if-clause, and would have (rarely could have) with a past participle is used in the main clause.

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More about Conditional Sentences

If-clauses without an If. An if-clause can be introduced with other terms such as when, unless, provided that and as long as or by using inversion (e.g., Were he available, he would be selected.)

• I will swim unless the water is too cold.
• I will swim as long as the water is not too cold.
• I will swim provided that the water is not too cold.

When they introduce an if-clause, when, provided that and as long as can usually be replaced with if. Also, unless could be replaced with an if..not construction (e.g., if the water is not too cold). So, the term if-clause, despite being disliked by some grammarians, is pretty accurate. It's certainly convenient.

Mixed Conditionals. Occasionally, a conditional sentence will "steal" the structures from two different types of conditional sentences. This most commonly occurs with a conditional sentence that uses the structure of a second-conditional sentence for one clause and the structure of a third-conditional sentence for the other. These are called mixed conditionals.

• If we were smarter, we wouldn't have set off in this weather.
(The if-clause is second-conditional structure. The main is third-conditional structure.)
• If you had checked the weather, we wouldn't be stranded now.
(The if-clause is third-conditional structure. The main is second-conditional structure.)

Mixed conditionals like these are typically used to express regret for past action or past inaction.

Why Conditional Sentences Are Important

Fortunately, the vast majority of native English speakers can create conditional sentences of all 4 "flavours" and the mixed "flavours" without tripping themselves up. It's because native English speakers are naturally great at tenses. That said, there are some fairly common hiccups related to tense worth covering and also a point on using commas.

(Point 1) Using a comma with an if-clause.

When the if-clause precedes the main clause, use a comma after the if-clause.

• If I were white, I could capture the world. (African-American actress Dorothy Dandridge, 1922-65)
• If you steal from one author, it's plagiarism; if you steal from many, it's research. (Playwright Wilson Mizner)

If the main clause precedes the if-clause, don't use a comma before the if-clause (unless you think it helps the reader).

• Dreams grow if you grow. (Author Zig Ziglar)
• There are consequences if you act militarily, and there are big consequences if you don't act. (US Diplomat Dennis Ross)

Here's an example that sums everything up:

• There are economic risks if we leave. If we remain, there are economic risks. (Politician Michael Gove)

(Issue 2) Using the wrong tense in one of your clauses.

Tense errors can creep in. Below are the most common ones with each structure.

Zero-conditional Structure. To express something as a fact, writers should use the zero-conditional structure (if + simple present tense, simple present tense). However, writers sometimes use the first-conditional structure (if + simple present tense, simple future tense), which states the result of a possible future event occurring.

• If you sleep, you will dream.
• When dogs die, they will go to doggy heaven.
(In both examples, the will should be deleted.)

With this mistake, the sentence structure is grammatically sound. It's the wrong sentence structure though, which affects the intended meaning.

First-conditional Structure. With the first-conditional structure, writers sometimes use the simple future tense (instead of the simple present tense) in the if-clause.

• If you will get some sleep, you will feel better.
• You can have everything in life you want if you will just help other people get what they want. (Author Zig Ziglar)
(In both examples, the will should probably be deleted.)

These haven't been marked as wrong because this structure is sometimes used to emphasize that the future action must occur. (And, that's a good get-out if you're ever picked up for this mistake.)

Second-conditional Structure. With the second-conditional structure, writers sometimes use the simple present tense (instead of the simple past tense) in the if-clause.

• If you become an insomniac, you would understand.
(If you became an insomniac would be correct.)

The next most common mistake is to use will (instead of would) in the main clause.

• If you became an insomniac, you will understand.
(You would understand would be correct.)

Third-conditional Structure. With the third-conditional structure, writers sometimes use would have (instead of the past perfect tense) in the if-clause.

• If you would have slept last night, you would have beaten your record.
(If you had slept last night would be correct.)

Key Points