The Purpose of a Sentence

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While the other sections in this module describe how sentences are constructed, this section describes why they have been written: to state facts, conjectures or arguments, give commands or ask questions.

The declarative sentence

It is quite common for entire texts or reports to be written using only declarative sentences. This type of sentence simply states a fact or argument without requiring an answer or action from the reader.

Declarative sentences are punctuated with a period:

• Ottawa is the capital of Canada.
• The distinction between deconstruction and post-modernism eludes me.
• Joe asked which path leads back to the lodge.

Note that the last example is an indirect question, which is not the same as an interrogative sentence. Only a direct question makes a sentence interrogative.

The interrogative sentence

An interrogative sentence asks a direct question and always ends in a question mark:

• Who can read this and not be moved?
• How many roads must a man walk down?
• Does money grow on trees?

Note that an indirect question does not make a sentence interrogative:

Direct/Interrogative

When was Lester B. Pearson prime minister?

Indirect/Declarative

I wonder when Lester B. Pearson was prime minister.

A direct question requires an answer from the reader, while an indirect question does not.

The rhetorical question

As a general rule, since texts are written to present information or to make an argument, they do not contain many direct questions. There is, however, a special type of direct question called the rhetorical question—that is, a question that the reader is not expected to answer:

• Why did the War of 1812 take place? Some scholars argue that it was simply a land grab by the Americans . . .

If not overused, rhetorical questions can be a very effective way to introduce new topics; if this device is used too often, however, the writer may sound patronizing.

The exclamatory sentence

An exclamatory sentence, or exclamation, is simply a more forceful version of a declarative sentence marked at the end with an exclamation mark:

• The butler did it!
• How beautiful this river is!
• Some towns in Upper Canada lost up to a third of their population during the cholera epidemics of the early nineteenth century!

Exclamatory sentences are common in speech and (sometimes) in fiction, but over the last 200 years they have almost entirely disappeared from formal writing, except for direct quotations. Note that an exclamation mark can also appear at the end of an imperative sentence.

The imperative sentence

An imperative sentence gives a direct command. This type of sentence can end either with a period or with an exclamation mark depending on how forceful the command is:

• Sit!
• Read this book for tomorrow.

You should not generally use an exclamation mark with the word please:

• Wash the windows!
• Please wash the windows.

You should avoid imperative sentences in formal writing. If you use an imperative sentence, it should contain only a mild command and end with a period:

• Consider the Incas.

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