Reason, Result, and Purpose

English has three closely related functions that often appear in the same conversation: reason explains why something happens, result describes what happens as a consequence, and purpose describes what something is for. Each function has its own set of linking words, and choosing the wrong one is a common source of errors.

Reason: why something happens

because + clause

Because is the most direct way to state a reason. It connects two clauses and puts full emphasis on the explanation.

I stayed home because I was sick.

The flight was cancelled because of a technical fault.

She passed the exam because she studied every evening.

The because-clause usually comes second. When it comes first, add a comma before the main clause.

Because the restaurant was full, we decided to cook at home.

since and as

Since and as also introduce reasons, but with a lighter touch. They work best when the reason is already known or obvious to the listener.

Since you already have the tickets, I'll meet you at the entrance.

As it was getting dark, we turned on the headlights.

Both since and as tend to appear at the beginning of the sentence. They are slightly more formal than because and put less emphasis on the reason itself.

Note that since and as also have time-related meanings (since Monday, as we were leaving). Context almost always makes the intended meaning clear, but if there is any risk of confusion, because is the safest choice.

because of and due to + noun

When the reason is expressed as a noun rather than a full clause, use because of or due to.

The match was postponed because of the rain.

Several flights were delayed due to thick fog.

She missed the meeting because of a family emergency.

Both phrases work the same way: preposition + noun phrase. Due to is slightly more formal and appears more often in written English.

STRUCTURE	EXAMPLE
because + clause	because it was raining
because of + noun	because of the rain
due to + noun	due to the rain

A frequent mistake is mixing the two patterns: because of it was raining or due to it was raining. If a subject and verb follow, use because. If only a noun follows, use because of or due to.

Result: what happens as a consequence

so

So is the everyday conjunction for results. It connects a cause to its outcome in a single sentence.

It was raining, so we stayed inside.

The shop was closed, so I went to the one across the street.

He forgot his wallet, so Anna paid for lunch.

The so-clause always comes second. A comma normally separates the two parts.

therefore, consequently, as a result

These linking adverbs do the same job as so but belong to a more formal register. They usually appear at the start of a new sentence or after a semicolon.

The road was blocked. Therefore, we took a different route.

Sales dropped sharply in March. As a result, the company cut its budget.

The evidence was inconclusive; consequently, the case was dismissed.

Unlike so, which joins two clauses inside one sentence, these adverbs connect two independent sentences. They are followed by a comma when they open a sentence.

so ... that and such ... that

These structures express a result that follows from an extreme degree or quality.

So + adjective/adverb + that:

It was so cold that the lake froze.

She spoke so quietly that nobody heard her.

The suitcase was so heavy that I could barely lift it.

Such + (a/an) + noun phrase + that:

It was such a cold night that the lake froze.

He told such a funny story that everyone laughed.

They made such good coffee that I ordered a second cup.

The difference is purely grammatical: so modifies an adjective or adverb, such modifies a noun phrase. The meaning stays the same.

PATTERN	WHAT FOLLOWS	EXAMPLE
so ... that	adjective / adverb	so tired that ...
such ... that	(a/an) + noun phrase	such a long day that ...

Purpose: what something is for

to + infinitive

The simplest way to express purpose is to + infinitive. It answers the question what for?

I went to the shop to buy milk.

She called the hotel to book a room.

He saved money for months to buy a bicycle.

This structure requires the same subject for both verbs. I went and I buy share the subject I, so the infinitive works. If the subjects are different, use so that instead.

in order to and so as to

In order to and so as to are more formal alternatives to to. The meaning is identical.

She left early in order to catch the first train.

The company hired extra staff so as to meet the deadline.

In everyday speech, the plain to-infinitive is almost always enough. In order to and so as to appear more often in written or professional English.

Negative purpose

For negative purpose, use in order not to or so as not to. The plain not to sounds awkward in most cases.

He whispered so as not to wake the baby.

I wrote it down in order not to forget.

She took a taxi so as not to be late.

so that + clause

So that introduces a purpose clause with its own subject and verb. This is the only option when the two actions have different subjects.

I'll write it down so that I don't forget.

She left a note so that her flatmate would know where she was.

He turned off the music so that the neighbours could sleep.

So that clauses often contain can, could, will, or would — because purpose naturally points toward ability or future action.

Quick reference

Reason

because + clause (neutral)
since, as + clause (slightly formal)
because of, due to + noun (neutral / formal)

Result

so + clause (neutral)
therefore, as a result + sentence (formal)
so + adjective + that + clause (neutral)
such + noun + that + clause (neutral)

Purpose

to + infinitive (neutral)
in order to, so as to + infinitive (formal)
so that + clause (neutral)

Common mistakes

because vs. because of

The game was cancelled because of it was raining

The game was cancelled because it was raining.

She stayed home because the headache

She stayed home because of the headache.

so vs. so that

I set an alarm so that not be late

I set an alarm so as not to be late.

I called her so that ask a question

I called her to ask a question.

so ... that vs. such ... that

It was such cold that we stayed inside

It was so cold that we stayed inside.

She is so a talented singer that everyone stopped

She is such a talented singer that everyone stopped.

Word order with so

So we stayed inside, it was raining

It was raining, so we stayed inside.

Negative purpose

He spoke quietly to not disturb anyone

He spoke quietly so as not to disturb anyone.

She closed the door for not wake the children

She closed the door in order not to wake the children.

due to + clause

The delay was due to the train broke down

The delay was due to the train breaking down.

The shop closed due to there were no customers

The shop closed because there were no customers.

Reason: why something happens

because + clause

Because is the most direct way to state a reason. It connects two clauses and puts full emphasis on the explanation.

I stayed home because I was sick.

The flight was cancelled because of a technical fault.

She passed the exam because she studied every evening.

The because-clause usually comes second. When it comes first, add a comma before the main clause.

Because the restaurant was full, we decided to cook at home.

since and as

Since and as also introduce reasons, but with a lighter touch. They work best when the reason is already known or obvious to the listener.

Since you already have the tickets, I'll meet you at the entrance.

As it was getting dark, we turned on the headlights.

Both since and as tend to appear at the beginning of the sentence. They are slightly more formal than because and put less emphasis on the reason itself.

because of and due to + noun

When the reason is expressed as a noun rather than a full clause, use because of or due to.

The match was postponed because of the rain.

Several flights were delayed due to thick fog.

She missed the meeting because of a family emergency.

Both phrases work the same way: preposition + noun phrase. Due to is slightly more formal and appears more often in written English.

STRUCTURE	EXAMPLE
because + clause	because it was raining
because of + noun	because of the rain
due to + noun	due to the rain

Result: what happens as a consequence

so

So is the everyday conjunction for results. It connects a cause to its outcome in a single sentence.

It was raining, so we stayed inside.

The shop was closed, so I went to the one across the street.

He forgot his wallet, so Anna paid for lunch.

The so-clause always comes second. A comma normally separates the two parts.

therefore, consequently, as a result

These linking adverbs do the same job as so but belong to a more formal register. They usually appear at the start of a new sentence or after a semicolon.

The road was blocked. Therefore, we took a different route.

Sales dropped sharply in March. As a result, the company cut its budget.

The evidence was inconclusive; consequently, the case was dismissed.

Unlike so, which joins two clauses inside one sentence, these adverbs connect two independent sentences. They are followed by a comma when they open a sentence.

so ... that and such ... that

These structures express a result that follows from an extreme degree or quality.

So + adjective/adverb + that:

It was so cold that the lake froze.

She spoke so quietly that nobody heard her.

The suitcase was so heavy that I could barely lift it.

Such + (a/an) + noun phrase + that:

It was such a cold night that the lake froze.

He told such a funny story that everyone laughed.

They made such good coffee that I ordered a second cup.

The difference is purely grammatical: so modifies an adjective or adverb, such modifies a noun phrase. The meaning stays the same.

PATTERN	WHAT FOLLOWS	EXAMPLE
so ... that	adjective / adverb	so tired that ...
such ... that	(a/an) + noun phrase	such a long day that ...

Purpose: what something is for

to + infinitive

The simplest way to express purpose is to + infinitive. It answers the question what for?

I went to the shop to buy milk.

She called the hotel to book a room.

He saved money for months to buy a bicycle.

This structure requires the same subject for both verbs. I went and I buy share the subject I, so the infinitive works. If the subjects are different, use so that instead.

in order to and so as to

In order to and so as to are more formal alternatives to to. The meaning is identical.

She left early in order to catch the first train.

The company hired extra staff so as to meet the deadline.

In everyday speech, the plain to-infinitive is almost always enough. In order to and so as to appear more often in written or professional English.

Negative purpose

For negative purpose, use in order not to or so as not to. The plain not to sounds awkward in most cases.

He whispered so as not to wake the baby.

I wrote it down in order not to forget.

She took a taxi so as not to be late.

so that + clause

So that introduces a purpose clause with its own subject and verb. This is the only option when the two actions have different subjects.

I'll write it down so that I don't forget.

She left a note so that her flatmate would know where she was.

He turned off the music so that the neighbours could sleep.

So that clauses often contain can, could, will, or would — because purpose naturally points toward ability or future action.

Quick reference

Reason

because + clause (neutral)
since, as + clause (slightly formal)
because of, due to + noun (neutral / formal)

Result

so + clause (neutral)
therefore, as a result + sentence (formal)
so + adjective + that + clause (neutral)
such + noun + that + clause (neutral)

Purpose

to + infinitive (neutral)
in order to, so as to + infinitive (formal)
so that + clause (neutral)

Common mistakes

because vs. because of

The game was cancelled because of it was raining

The game was cancelled because it was raining.

She stayed home because the headache

She stayed home because of the headache.

so vs. so that

I set an alarm so that not be late

I set an alarm so as not to be late.

I called her so that ask a question

I called her to ask a question.

so ... that vs. such ... that

It was such cold that we stayed inside

It was so cold that we stayed inside.

She is so a talented singer that everyone stopped

She is such a talented singer that everyone stopped.

Word order with so

So we stayed inside, it was raining

It was raining, so we stayed inside.

Negative purpose

He spoke quietly to not disturb anyone

He spoke quietly so as not to disturb anyone.

She closed the door for not wake the children

She closed the door in order not to wake the children.

due to + clause

The delay was due to the train broke down

The delay was due to the train breaking down.

The shop closed due to there were no customers

The shop closed because there were no customers.

Reason, Result, and Purpose

Reason: why something happens

because + clause

since and as

because of and due to + noun

Result: what happens as a consequence

so

therefore, consequently, as a result

so ... that and such ... that

Purpose: what something is for

to + infinitive

in order to and so as to

Negative purpose

so that + clause

Quick reference

Common mistakes

More in this topic

Reason, Result, and Purpose

Reason: why something happens

because + clause

since and as

because of and due to + noun

Result: what happens as a consequence

so

therefore, consequently, as a result

so ... that and such ... that

Purpose: what something is for

to + infinitive

in order to and so as to

Negative purpose

so that + clause

Quick reference

Common mistakes

More in this topic