I don't understand why in the sentence " what makes you think so" we don't use "do" like "what does make you think so?" It's present simple. It is a question. What do I miss here? I would be grateful for another examples!

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    What is the subject of makes. The rule of do-support only applies when an auxiliary verb is required (like it is for negation or subject-auxiliary inversion), but subject-auxiliary inversion does not apply to subjects that are wh-words in questions -- it's Who hit you?, not *Who did hit you? or *Did who hit you? There are different rules and they interact together; do-support is part of the mix. Commented Oct 4, 2016 at 19:35
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    Thank you @JohnLawler ! It makes sense. It's like "Who called you last night? ". Who is the subject, so I don't use "do".
    – user278618
    Commented Oct 4, 2016 at 19:47
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    Funny thing, I find these explanations using formal grammar terms overly complex for English learners. I taught English seven years and never provided technical linguistic explanations....just saying....by the way: /Who did hit you/ is grammatical whereas Did who hit you? is not...
    – Lambie
    Commented Oct 4, 2016 at 23:02

2 Answers 2


The use of do-support within a wh-word question only normally occurs in contexts where a possible answer has already been (explicitly or implicitly) provided and rejected...

We all know Kojak hates you, so answer me this: Who does love ya, baby?

You can get more or less the same implication without do-support by placing heavy stress on Who in the above example, but note that do-support applies to every main verb in English, except auxiliary verbs (and the verb be is always treated as an auxiliary verb, even if it's the only verb in its clause). Thus in the case of...

We all know Kojak hates you, so answer me this: Who is your secret lover, baby?

...where the implied "rejection" (of a default or previously-suggested response) can be conveyed equally well by placing heavy stress on either Who or is. Offhand I can't think of any obvious difference in nuance depending which of those two words you stress, but you definitely can't include does there.

In Shakespeare's time, OP's example What does make you think so? could feasibly occur in contexts where no such rejection is implied, in which case the word does wouldn't be stressed. But today it would only be likely with that stress, in contexts where some possible justification for the addressee's belief has already been proposed and rejected...

If you still think he's innocent despite all the evidence, what does make you think so?

(Which I admit is a little contrived, but again the same effect can be acheived by stressing what.)


You can think of it as

What makes you think so?
what causes you to think that way

Why do you think so?
what causes you to think that way

I really don't understand him, what does make him think that way?

in the last case (with heavy emphasis on does) does is used as an intensifier for emphasis

What does make you think so?

is more of a rhetorical question, whereas

What makes you think so?

is a standard question asking one's thinking behind an answer or belief.

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