No Idea Why

[Ronald Wieck]

The sentence "I have no idea why she considers such information relevant," appears to lack a preposition. Should it read, "I have no idea OF why, etc." or "I have no idea ABOUT why, etc."? In speaking, I would omit any prepositions and simply use the first version. Can you suggest why proper usage favors one form over the other?

 

[Matthew Wai]

I think 'why' is an adverb; that's why a preposition is not needed before it.

 

[Midlands Hammer]

This is a very interesting question. Consider these similar sentences:

1. I don't know why he did it.
2. I have no information about/on why he did it.

In 1. the meaning is similar to "I have no idea why..." but in this case the grammar is more obvious because "know" is a verb which can take a direct object e.g. I don't know the answer.

In 2. the form is initially the same as "I have no idea" (have + no + object noun) but then we need a preposition after "information". Omitting the preposition would feel wrong, and be wrong, in my opinion.

So my tentative conclusion is that "I have no idea why" is idiomatic and perhaps the "of" has disappeared from common usage with the passage of time. I can imagine the phrase being said with "of" but it sounds old-fashioned.

 

[GoesStation]

So my tentative conclusion is that "I have no idea why" is idiomatic and perhaps the "of" has disappeared from common usage with the passage of time. I can imagine the phrase being said with "of" but it sounds old-fashioned.

I have no idea of why sounds wrong, not old-fashioned. I have no idea why follows the same construction as I have no idea how. Neither phrase requires of.

 

[Raymott]

You've softened your argument with your last sentence. You were arguing that it was wrong, not simply unnecessary.
I agree with your softened argument that "I have no idea of how he did it" is unnecessary, but I'd say it's grammatical.
If you said, "I have no idea", it's likely that someone would ask "About what?" - indicating that a preposition is natural there. To this you might answer, "About how he did it."

 

[GoesStation]

You've softened your argument with your last sentence. You were arguing that it was wrong, not simply unnecessary.
I agree with your softened argument that "I have no idea of how he did it" is unnecessary, but I'd say it's grammatical.
If you said, "I have no idea", it's likely that someone would ask "About what?" - indicating that a preposition is natural there. To this you might answer, "About how he did it."

I agree there's room for a preposition after no idea. I don't think of is the right one.

 

[tzfujimino]

"I have no idea as to why ..." also sounds good to me.

 

[Matthew Wai]

I found a relevant thread https://www.usingenglish.com/forum/...rect-Explanation-why-vs-explanation-as-to-why

 

[Midlands Hammer]

I have no idea of why sounds wrong, not old-fashioned. I have no idea why follows the same construction as I have no idea how. Neither phrase requires of.

Check this usage here: I have no real idea of what it must be like to face a life tariff as a teenager. (from http://fraze.it/n_search.jsp?q=have+no+idea+of&l=0) This is from "The Guardian".

 

[Matthew Wai]

'What' is a pronoun. Can 'why' be so?

 

[GoesStation]

Check this usage here: I have no real idea of what it must be like to face a life tariff as a teenager. (from http://fraze.it/n_search.jsp?q=have+no+idea+of&l=0) This is from "The Guardian".

That's fine. I can't think of a natural phrase with no idea of why in it.

 

[GoesStation]

'What' is a pronoun. Can 'why' be so?

No. That explains why the Guardian's phrase works and OP's doesn't.

 

[Midlands Hammer]

'What' is a pronoun. Can 'why' be so?

I don't know if professional grammarians would describe "what" and "why" as pronouns. However, I would say that, for the purposes of the discussion at hand, "what" and "why" can be described as pronouns (or otherwise) in the same way.

What = the thing that
Why = the reason that

 

[Midlands Hammer]

That's fine. I can't think of a natural phrase with no idea of why in it.

But check my response to the same point. I don't think the classification of "what" or "why" as pronouns is relevant to the issue.

 

[Midlands Hammer]

That's fine. I can't think of a natural phrase with no idea of why in it.

I never stated that "no idea of why" was natural. The point I was making is that an original "of" (or other preposition) which has been lost over time may explain this as a current idiomatic usage. I can't think of any grammar rule to explain why the absence of a preposition would be correct in this case.

 

[Matthew Wai]

Why = the reason that

If so, does 'the reason why' mean 'the reason the reason that'?

 

[Midlands Hammer]

If so, does 'the reason why' mean 'the reason the reason that'?

Effectively, yes. "The reason why" is tautologous but it's natural and doesn't feel tautologous to a native speaker in practice.

 

[Matthew Wai]

I can't think of any grammar rule to explain why the absence of a preposition would be correct in this case.

'Why' is a conjunction. Can it be the explanation?

 

[Midlands Hammer]

How do you know that?

From my experience. Do you disagree? Collins mentions it in an example sentence in its dictionary definition: http://www.collinsdictionary.com/dictionary/english/why

 

[Midlands Hammer]

'Why' is a conjunction. Can it be the explanation?

I don't think that its use as a conjunction explains this usage. Collins has this good example: He still could not throw any further light on why the elevator could have become jammed. http://www.collinsdictionary.com/dictionary/english/why

The preposition "on" is necessary in this sentence. I still think that "no idea why" without a preposition is purely idiomatic. If anyone comes up with another theory, then I'd be interested.