Please help me to understand when should I use an article before reason and when I should not use any article before reason.


(A) I have reason to do this.

(B) I have a good reason to do this.

(C) I have a reason to do this.

(D) I have some reason to do this.

I meant to say all sentences in the same way, just want to confirm when should I use an article and when I should not. Please also check all sentences are correct or not.

Thanks in advance.

  • 1
    I don't know why, but (C) seems like it would flow better if it said, "I have a reason for doing this."
    – J.R.
    Commented Feb 21, 2014 at 14:34

2 Answers 2


There are different uses of the noun "reason" here.

B,C,D) For these it is a countable noun.

I have reasons for doing this.

Note the use of the plural. This looks very similar to (A) but is using "reason" as a countable noun.

0) Another use of "reason" is an uncountable noun.

There is reason in madness.

A) Example (A) is a phrase "to have reason". Here "reason" means that what you do is reasonable, you could justify it. It is from the uncountable noun. So what you do can be justified.

I have reason to believe you.

I have good reason to do this.

Or you could justify the actions of someone else.

He has reason to do that.

Sometimes, you can justify your expectation of something even if it is not true or provably true,

He has reason to know.

  • Your first assertion is simply wrong. Since to do this isn't a particularly common form (idiomatically we'd normally say for doing this), I checked to do so in Google Books. The results for that preceded by OP's four variants are A:32600, B:4910, C:6550, D:1830. And I don';t agree that A derives from "being reasonable" - it's primarily a singular reference to [a] specific reason. Commented Feb 22, 2014 at 17:17
  • @FumbleFingers I mean that the countable forms, are more common. B, C and D being examples of countable forms. The non-countable form A is less common. p.s. hunter also says countable forms are more common than the non-countable forms. hunter: "we don't use the mass noun construction very often." p.p.s. I disagree with hunter when I think D is also an example of the countable form.
    – QuentinUK
    Commented Feb 22, 2014 at 23:42
  • I'm not sure what you mean by "the countable forms, are more common". The counts (sorry! :) from GB show that A occurs far more often than all the others put together. I had to change "this" to "so" because all OP's variants are uncommon (barely a dozen results in total). I know things change again if we switch to for doing this, but that's a different construction again. Hunter is mistaken - D is perfectly okay in the right context for both senses - countable: some particular but unspecified reason; uncountable: some aspect or amount of reason. Commented Feb 23, 2014 at 0:05
  • @FumbleFingers I could not reproduce your results eg "I have reason to do so." google.co.uk/#q=%22I+have+reason+to+do+so.%22&tbm=bks returns "About 12,100 results" but has a list of 16 books, so I don't know what's going on.
    – QuentinUK
    Commented Feb 23, 2014 at 0:15
  • Different searches get different results, eg Google Web "There is a reason" google.co.uk/#q=%22There+is+a+reason%22 = About 1,430,000,000 results but also "There is reason" google.co.uk/#q=%22There+is+reason%22 = About 40,500,000 results.
    – QuentinUK
    Commented Feb 23, 2014 at 0:23

This is interesting.

Grammatically, what is going on is that "reason" is being interpreted both as a "mass noun" (which never takes "a") in sentences (A) and (D) and as a "count noun" (which obligatorily takes "a") in sentences (B) and (C). "A reason" refers to one specific entity (I am doing this because it will cause me to earn 1000 dollars next year) whereas "reason" is more ambiguous, possibly refering to lots of "reasons" or to a reason that the speaker does not wish to specify.

Both (B) and (C) are fine and only differ by the word "good" which means something logical. To me (American) (A) sounds formal and (D) sounds wrong, or almost wrong, because we don't use the mass noun construction very often. In fact the only time I personally use it is in the specific phrase "I have reason to believe that [x]"

It would be interesting to hear from other speakers on this.

  • actually following JR's comment above, I think also (D) sounds better if you use the participle instead of the infinitive; I have no clue why.
    – hunter
    Commented Feb 21, 2014 at 15:57

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