The most common way to talk about why something happened in English is to use a reason, purpose, or result clause. These are all types of subordinate clausesNo definition set for subordinate clausesLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. that we use when we are describing why something happened, but they each do something a little different.
A reason clause describes the cause of an event.
I decided to stay home because it was raining.
A purpose clause describes the goal or ideal outcome of an action.
I got up early so that I would be on time for my flight.
A result clause describes the effect of a previous action.
I took a wrong turn so I was late for my interview.
(Notice that you ask “why?” about a result clause; it does not answer the question “why?”)
Each type of clause follows slightly different rules. In this post, we’ll look at some of the most important ways to create clauses of reason, purpose, and result. Along the way, we’ll introduce you to some other ways to explain why something happened, including how to use prepositions of cause, like because of and due to, and how and why to use the English phrase in case.
Why read on? Maybe because you want to learn more about how to explain why things happen in English! Let’s go!
To form reason, purpose, and result clauses, you will usually need to start with a word or phrase called a conjunction. Reason clauses will start with a conjunction of reason, purpose clauses will start with a conjunction of purpose, and result clauses will start with a conjunction of result.
Conjunction of reason:
I decided to stay home because it was raining.
Conjunction of purpose:
I got up early so that I would be on time for my flight.
Conjunction of result:
I took a wrong turn so I was late for my interview.
Reason, purpose, and result clauses are all types of subordinate clauses. A subordinate clause is a kind of clauseNo definition set for clauseLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. that gives more information about the central situation or event a sentence describes.
The part of the sentence that describes the central situation or event is called the main clause. In the examples above, the main clause is the part of the sentence that is not in bold.
In some kinds of subordinate clauses in English, we do not use the future tense:
❌ Larry will be tired when he will go to bed.
✅ Larry will be tired when he goes to bed.
But you can use the future tense in clauses of reason, purpose, and result.
✅ Larry will be tired tomorrow because he will stay up late tonight.
✅ Larry will go to bed early so that he will not be tired tomorrow.
✅ Larry will stay up late tonight so he will be tired tomorrow.
Let’s have a look at the different conjunctions that you can use to introduce a reason, purpose, or result clause in English. As you’ll see, each word has slightly different rules, and sometimes you will give a reason, purpose, or result without using a conjunction at all!
The most common words and phrases we use to start a reason clause in English are: because, as, now (that), and since. These are also called conjunctions of reason. English conjunctions of reason are not very different in meaning, but they are a little different in how we use them. Let’s look at each of them one by one!
Because is the most common and useful English conjunction of reason. Here are some examples:
I am going to get wet going to the shop because it is raining.
He had called his mom because he was lonely.
Because he was hungry, he ate a sandwich.
I am sitting on the chair because John is going to want to sit on the couch.
As can be a conjunction of reason as well, but it is a little more formal than because.
I am wet as it is raining.
They went to the castle as it was nearby.
As it is Friday, I will go out with friends.
The word as can also be a conjunction of time with the same meaning as while, so “I watch baking shows as I cook” can mean: I watch baking shows because I cook. (conjunction of reason) OR I watch baking shows while I cook. (conjunction of time).
You will usually use now (that) if you have been waiting for the cause to happen for a while. It is often used in stories.
Now that we live in Arizona, we can go walking in the mountains.
I understand this song better now that I speak English!
In spoken English or casual writing, you can leave out that.
Now we live in Arizona, we can go walking in the mountains.
I understand this song better now I speak English!
Even though now that contains the word now, which we usually use to talk about the moment of speech, we can use now that to talk about the “now” of the past:
Larry was happy now that his dog had learned a trick.
Since is a common conjunction of reason in spoken English, but it is less common in formal writing.
I am wet since it is raining.
I have been studying since I have a test on Friday.
Since she likes animals, her parents bought her a kitten.
Since can also be a conjunction of time which means in the time that passed after. For example, “I haven’t eaten anything since I left the house this morning” could mean:
I haven’t eaten anything because I left the house this morning. (conjunction of reason)
I haven’t eaten anything in the time that passed after I left the house this morning. (conjunction of time)
If you want to be very clear, use because instead of since.
The conjunction for is used to introduce a reason clause in old-fashioned or literary English.
His horse was tired, for he had been traveling since dawn.
Prudence didn’t know what to do, for she did not want to offend anyone.
The conjunction for is sometimes called a coordinating conjunctionNo definition set for coordinating conjunctionLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. because it is one of the FANBOYS conjunctions, which follow special punctuation and grammar rules. So there are two unusual rules to follow when you use for:
Do not start a sentence with for + clause.
Always use a comma before a clause beginning with for.
When the cause of an event is a person, thing, or circumstance, we don’t need to use a whole clause to give the reason for something. Instead, we use a preposition of reason + noun. Here are some of the most common prepositions of reason in English
Preposition of reason | Example |
|---|---|
because of → most common! | We lost the game because of John. |
due to | He was absent due to an illness. |
as a result of | The toddler became tired as a result of a long day. |
as a consequence of | He was expelled as a consequence of breaking the rules. |
owing to | She was famous owing to her great wealth. |
The preposition because of is the most common preposition of reason in spoken English. The others are mostly used in formal speech and writing.
The main phrase we use to start a purpose clause in English is so that, but you can also just use a clause with an infinitive verb. Sometimes these infinitive purpose clauses can come after the conjunctions so as and in order. Let’s take a look at purpose clauses in a bit more detail.
So that is the simplest way to introduce a purpose clause in English. Here are some examples:
She left home so that she could see the world.
He made dinner at 5 pm so that he could go to bed early.
So that they could watch the sunset, they went outside.
It is very common to leave out the word that and just say so. This sounds a little less formal, but we do it in both writing and speech.
She left home so she could see the world.
The clause that follows so that will almost always have a modal verbNo definition set for modal verbLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.:
If the purpose clause describes the goal of a past action, you will need to use could or would (rarely might)
We brought an iPad so that my son would have something to do in the car.
If the purpose clause describes the goal of a present or future action, you will use can or will (rarely may)
We are bringing an iPad so that my son will have something to do in the car.
The word so is also a conjunction of result. Read on for some tips about how to tell the difference between so (that) and so!
You can use so as or in order with an infinitive verb to create a purpose clause as well.
My mom read many books so as to understand the topic fully.
He changed the channel in order to watch the ten o’clock news.
Most often, though, English speakers will just use the infinitive verb by itself. This is probably the most common way to form a purpose clause in everyday English.
My mom read many books to understand the topic fully.
He changed the channel to watch the ten o’clock news.
Even without so as and in order, you can put the purpose clause before the main clause.
He moved to Rome to learn Italian.
To learn Italian, he moved to Rome.
Check out our post on infinitive verbs in English to learn more about how to use infinitive verbs to give the purpose for an action.
Here are some things to remember, if you use a clause with an infinitive verb to give the purpose of an action:
The subject of the subordinate clause will always be understood to be the same as the subject of the main clause:
Sandra's family went to Beijing to see the Forbidden City.
The subject must always be understood, it can’t be a noun or pronoun:
❌ Sandra's family went to Beijing they to see the Forbidden City
You can use for + noun to say that the noun is the goal of some action. For example:
Jackson and Anne went out for dinner.
I made a cake for my mother.
Often we use for before a gerund (verb + -ing) to describe the purpose of an object, but this is not used to describe the purpose of an action.
✅ This soap is for washing dishes.
❌ I went to the zoo for watching the animals.
Most result clauses will start with the word so, but conjunctive adverbs like as a result, therefore, thus, consequently, and subsequently can also introduce a result. There are some grammatical differences to learn between using so and using conjunctive adverbs to give a result clause. Let’s have a look!
So is the most common word used to introduce result clauses in English. Here are some example sentences with so:
Bobby didn’t eat his vegetables, so he was not allowed to have any dessert.
She worked out at the gym every day, so she is now really strong.
The conjunction so is one of the FANBOYS conjunctions, which follow special punctuation and grammar rules. There are two unusual rules to follow when you use so:
Do not start a sentence with a result clause that begins with so:
❌ So Bobby was not allowed to have any dessert, he didn’t eat his vegetables.
Always use a comma before a clause beginning with so.
We can also use the word so as part of the longer phrase and so. We usually use and sowhen we are telling a story.
Bobby didn’t eat his vegetables, and so he was not allowed to have any dessert.
She worked out at the gym every day, and so she got really strong.
The word so can also be used as a conjunction of purpose, as a reduced form of so that. How do you tell the difference?
When so is a conjunction of purpose, it will usually be followed by a modal verb: would, could, will, or can.
When so is a conjunction of result, it always follows a comma (but be careful, some writers forget this rule!)
Can you tell which sentence gives a purpose and which shows a result?
I studied my English, so I did well on my test.
I studied my English so I would do well on my test.
Several words and phrases like therefore, as a result, accordingly, thus, hence, subsequently, ergo, and consequently can also introduce result clauses. These phrases follow slightly different grammar rules from so and so they are called conjunctive adverbs, not conjunctions. Here is how to use conjunctive adverbs of result:
A conjunctive adverb is not used alone at the start of a result clause. If you want to make the result clause the second clause of your sentence, you will need to use the word and.
✅ Bobby didn’t eat his vegetables, and therefore he was not allowed to have dessert.
❌ Bobby didn’t eat his vegetables therefore he was not allowed to have dessert.
You can use a conjunctive adverb at the start of a sentence, after a semicolon (;), or after a dash (—). When you use a conjunctive adverb this way, it should always be followed by a comma.
It was raining. Therefore, I brought an umbrella.
She fell over; thus, she broke her arm.
He left his book outside — subsequently, it got wet in the rain.
In speech, these all sound like the start of a new sentence.
Watch out for the common punctuation error called a comma splice:
❌ She went for a drive without a map, therefore, she got lost.
✅ She went for a drive without a map; therefore, she got lost.
A conjunctive adverb cannot follow a comma!
You can use a conjunctive adverb before any phrase with a verb. It does not need to be part of a complete clause:
✅ She studied hard and thereby won a prize.
✅ We ate a good dinner and thus were happy.
A conjunctive adverb can also come in the middle or at the end of a clause or phrase. Usually it is separated out with commas.
✅ Her friend forgot his backpack and she, therefore, gave him a pencil.
✅ Maddie failed four classes, and she had to go to summer school, as a result.
Usually, you will put a reason, purpose, or result clause after the main clause in a sentence.
I am wet because it is raining.
Harriet brought an umbrella so that she would not get wet.
It rained, so you got wet.
However, reason and purpose clauses can come before the main clause too, as long as they are followed by a comma. This is more common in writing
Because it is raining, I am wet.
So that she would not get wet, Harriet brought an umbrella.
Result clauses, however, can ONLY follow the main clause. You cannot put them at the beginning of a sentence.
❌ So you got wet, it rained.
✅ It rained, so you got wet.
❌ Therefore, you got wet, it rained.
✅ It rained. Threrefore, you got wet.
Like reason, purpose, and result clauses, we use the conjunction in case to talk about why something happened, but it is a little different from conjunctions of reason, purpose, and result.
Specifically, we use the phrase in case to explain what you did to prepare for a possible situation. The phrase in case comes before the situation you have prepared for. A good synonym for in case is because… might…, as in:
Example with in case | Example with because... might... |
|---|---|
I took an umbrella in case it rained. | I took an umbrella because it might rain. |
Sarah is making extra dinner in case her guests are hungry. | Sarah made extra dinner because her guests might be hungry. |
The candidate wrote an acceptance speech in case she wins the election. | The candidate wrote an acceptance speech because she might win the election. |
But remember that the main clause still needs to describe an action someone took because the subordinate clause might happen.
✅ I am happy because I might win.
❌ I am happy in case I win.
The phrase in case is, therefore, a little like a conjunction of reason, but the reason is always an uncertain situation, and the main clause is always something you did to prepare, which makes this conjunction a bit different.
The phrase in case is also sometimes used to create conditional sentences without the word if.
In this article we covered how to describe why something happened in English. You saw that the main way to do this is with reason, purpose, and result clauses.
Reason clause (describes the cause) | Purpose clause (describes the ideal outcome) | Result clause (describes the effect) |
|---|---|---|
Starts with because, as, now (that), since, or for | Starts with so (that) | Starts with so or and so |
But we also introduced you to a few more concepts:
Prepositions of reason (aka prepositions of cause) like because of or due to come before nouns that cause an action.
The word for can come before nouns that describe the purpose or goal of an action.
The phrase in case comes before a possible situation when the main clause describes what you did to prepare for it.
Let’s put our knowledge into practice with some useful reason, purpose, and result clause activities for you to try.
