I have a co-worker that is always saying "Therefore, A B C" when the "A B C" isn't a conclusion from any sort of deductive reasoning. For example,

Me: ... thus, that's how it works.
Her: I think you are wrong about that. Therefore, I know I'm right.

I was wondering if this use of therefore is appropriate. Should therefore only be used (much as in the symbolic logic sense) when what's being concluded is beyond a reasonable doubt?

  • 3
    Sheer nonsense, yes, but grammatically correct.
    – rest_day
    Commented Jun 16, 2011 at 21:12
  • I just dont see how it could be grammatically correct when the argument isn't even fundamentally correct. There is no logical connection or connotation between the premise and the conclusion. Commented Jun 16, 2011 at 21:13
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    @Oghma: The purpose of grammar is not to check logic. They are technically unrelated. A blatantly untrue statement can be grammatically correct.
    – MrHen
    Commented Jun 16, 2011 at 21:16
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    @Oghma As mentioned in almost all the answers, therefore can be used to logically connect a premise with a conclusion that speaker thinks is correct.
    – rest_day
    Commented Jun 16, 2011 at 21:36
  • 1
    @Oghma: No problem. Of course, this doesn't make your friend any less wrong. :P
    – MrHen
    Commented Jun 16, 2011 at 21:46

3 Answers 3


No, therefore should not be reserved for conclusions beyond a reasonable doubt. It is merely a transition similar to thus or as such:

Therefore, I ordered pepperoni.

Thus, I ordered pepperoni.

As such, I ordered pepperoni.

The extended conversation could have been:

I like meat on my pizza. Therefore, I ordered pepperoni.

You can test for an appropriate use of therefore by flipping the sentence order and using because:

I ordered pepperoni because I like meat on my pizza.

The contention that the therefore segment should be restricted to perfect logical use is forgetting that the word really only serves to draw a causal link between statements.

I like red. Therefore, I painted my wall red.

There is no logic here. I am just explaining why I painted the wall red.

Now, if someone is using therefore as a logical link and the logic sucks, you can say that the argument is bad. But the use of therefore isn't the problem.

This $10 item is 50% off; therefore I am saving $6.

This is wrong, but the use of therefore isn't incorrect because it is simply communicating the thought. The communication is accurate; that makes therefore the appropriate word. Replacing therefore with a different word changes the meaning of the sentence (and could correct the logic) but the intent of the speaker no longer matches the communication.

Edit: Since there seems to be some confusion about the actual definition of the word, here is what my dictionary says:

for that reason; consequently : he was injured and therefore unable to play.

Reason, in this context does not mean "logic". It just means "why".

Why couldn't he play? / He was injured.

He was injured and therefore unable to play.

He was unable to play because he was injured.

It is worth noting that there is a strict logical use for the term therefore that explicitly means something akin to "logically derived from the previous statements" but that would be applicable to formations of the following:

  1. All men are mortal

  2. Aristotle is a man

  3. Therefore, Aristotle is mortal

This is commonly represented by three dots in a triangle (∴). But even in this case, the use of therefore is a signal of a specific meaning. If the conclusion is false, it was not an incorrect use of therefore but simply faulty logic. Removing or changing the word doesn't make the problem go away.

  • This definition of therefore gives some more ways to say "for that reason". COCA for therefore, spoken also has examples of use indicating a relationship between two ideas that makes sense to the speaker, but where one idea might not be a logical cause of the other (including self-reinforcing ideas like "These are things that computers are good at and, therefore, should be allowed to be good at").
    – aedia λ
    Commented Jun 16, 2011 at 21:19
  • But, even with your example @aedia, the definition says therefore is used to come to a logical conclusion of a premise just mentioned. So, if the logic isn't correct, therefore wouldn't be the proper term to use.... Right? Commented Jun 16, 2011 at 21:24
  • @Oghma: I edited some clarifications in. Hope that helps.
    – MrHen
    Commented Jun 16, 2011 at 21:33
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    @OghmaOsiris, take another example: "I'm good at writing; therefore, you should let me do the writing." This is grammatical and the use of "therefore" makes sense here, but my logic can still be wrong (we don't know without context). Perhaps my premise is flawed: I'm bad at writing. Perhaps my conclusion is flawed: you're a better writer, or you would benefit more from the practice. Even if you immediately tell me there's no connection and you're only letting me do the writing because you're tired, my statement was ok - I was using "therefore" to link two ideas that I thought were connected.
    – aedia λ
    Commented Jun 16, 2011 at 21:59
  • The creators of the artifical language Loglan distinguished four different kinds of "therefore" (and of "because"): logical, physical, motive, and reason/justification.
    – Colin Fine
    Commented Jun 17, 2011 at 11:37

Yes, you are right. 'Therefore' is used to link a statement which logically follows another one. It cannot be used in a standalone statement.

I would not say therefore should be used when something is being concluded beyond reasonable doubt. It can be used to connect two statements that

1) the user believes is logically correct

2) the user wants you to believe is logically correct.

For example, the following statement is grammatically correct, even though logically incorrect: "The sun moves from the east to the west. Therefore the sun is circling the earth".


It depends what you mean by 'should'. Therefore is used in the context of an argument, and if you are following the proper rules of argument should only be used to link a premise to a conclusion. But if you are merely trying to win the argument (following the rules of rhetoric), it's a very useful device to bolster a weak argument: "You want more benefits and lower taxes; therefore you should vote for me".

  • Therefore, I agree
    – JeffSahol
    Commented Jun 16, 2011 at 20:58
  • +1 but I'd like to note that "You want more benefits and lower taxes; therefore you should vote for me" sounds even weaker, because it draws attention to the supposed argumentative structure, which is doubtful. But that was probably your intention. Commented Jun 16, 2011 at 21:10

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