The conclusion is both are harmful.

My friends told me that you can not use 'is' and 'are' in the same sentence.

  • 34
    Your friends are wrong. There is one conclusion and two things that are harmful. The sentence would be clearer with a ’that’: “The conclusion is that both are harmful.”
    – Jim
    Mar 30, 2020 at 19:10
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    The sentence is correct. 'Both' refers to two elements and takes 'are' for the plural.
    – Elliot
    Mar 30, 2020 at 19:56
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    Personally I would insert "that" between "is" and "both" to give "My conclusion is that both are harmful" which would make it a bit easier to read. Otherwise it's correct.
    – BoldBen
    Mar 30, 2020 at 22:57
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    Using both "is" and "are" means that you might be mixing singular and plural and you should check to make sure, but in this case it's correct. Mar 31, 2020 at 4:36
  • 8
    A colon would clear things up a lot. Consider "The conclusion is: both are harmful"
    – AmagicalFishy
    Mar 31, 2020 at 5:13

6 Answers 6


When in doubt, I find it helpful to simplify the sentence. Consider these:

The conclusion is uncertain.
The conclusion is final.
The conclusion is X.

Clearly, whatever the conclusion is, it's singular and needs a singular verb.

Now let's look at what the actual conclusion is:

Both are harmful.

Again, clearly, "both" refers to two things and thus requires a plural verb, "are". You could check that by replacing both:

Cigarettes and gun battles are harmful.
Angry dragons and mean dogs are harmful.

Now, let's take that last conclusion example -- The conclusion is X. -- and replace X with what it actually is:

The conclusion is [both are harmful].

When you look at it that way, it becomes clear that the sentence as originally written is indeed correct.

My conclusion is that your friends are wrong.

  • 7
    Last conclusion exactly to the point!
    – Pac0
    Mar 31, 2020 at 14:41
  • @RogerSinasohn, is there a way to punctuate it to be more clear? The conclusion is: both are harmful etc.?
    – Nathan Goings
    Mar 31, 2020 at 22:46
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    I think that @BoldBen's suggestion of inserting "that" -- as in The conclusion is that both are harmful -- would go a long way to making it more clear. It sort of adds a pause, much as the colon would, without being unnatural. Mar 31, 2020 at 23:08

No. No, no, no. Send your friends back a grade.

Conclusion is singular. Use is.

Both is plural. Use are.


In relative , noun or adverbial clauses we often face these kinds of sentences. E.g “Who I am is not important.


You have two ideas together. One is that the conclusion is right. The other is that both A and B are harmful. You are putting these into one sentence and finding it troublesome.

You are also rushing by with spoken English and leaving out an implied word that explains things.

The conclusion is that both are purple.


It all depends on the way you define what sentence means in your context.

If you mean the string between two periods, then yes, a sentence can have an arbitrary number of conjugated verbs, and hence is and are in one sentence are allowed. For example:

The weather is fine and all people are happy.

If you consider a sentence to be the part containing subject and conjugated verb (or an infinitive sentence), then it is not possible. Then, the example above must be considered as two sentences that are contactenated.

The example in your question is really a sentence and its subclause - so it is one sentence in the first sense but two sentences in the latter sense. For better readability, there should be a that in between:

The conclusion is that both are harmful.

  • 1
    "the part containing subject and conjugated verb " - Isn't that the definition of a clause? How could you consider that a sentence?
    – wjandrea
    Mar 31, 2020 at 14:32
  • @wjandrea A clause is a part of sentence that is incomplete on its own. Mar 31, 2020 at 15:59
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    Not necessarily. You can have independent clauses, which could be their own sentences but aren't. In your example, The weather is fine and all people are happy are independent, so you could also write The weather is fine. All people are happy., though it sounds clunky.
    – wjandrea
    Mar 31, 2020 at 16:15
  • @wjandrea You say it: "Not necessarily." The Oxford definition of what a clause is is so blurry that I find it pretty useless. Many other languages do not have two different words for sentences and clauses although they also distinguish them quite well. Apr 1, 2020 at 7:18

No reason they can't be used in the same sentence, but for the sentence you provided it's incorrect.

The context of the question is "can you use both or only one", so "both" is a solution and therefore:

"The conclusion is [the use of] both is harmful."

In the original sentence, "The conclusion is both are harmful.", this is implying that both words "is" and "are" are independently harmful, and they are not both harmful.

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