I found the following sentence in The New York Times.

When people are in possession of their mental faculties, they are the experts on whether their lives are worth living. (SOURCE)

Now see the way this part - whether their lives are worth living. - is being used. It seems like it's a fused relative construction, and whether is being used as a relativizer.

But I have never known the word - whether - has ever been used as anything other than conjunction. So what is it here? Can anyone please explain the italic part in my quoted sentence?

I have found another sentence -

They are the experts on whether the output from these dams can easily and inexpensively be replaced, not fishery biologists. (SOURCE)

But this one is a person's comment on a blog post. But the former one is from a reputed source.

[For my own reference: some asides from StoneyB regarding the gap in the clause. HERE]

  • 2
    Whether is indeed employed as a relativizer here, and this use in fused relatives is really its core function. The "conjunctive" use is really just a specialized application of the fused relative construction. Commented Jan 24, 2016 at 13:49
  • @StoneyB Hmmm...I have never seen such usage...mostly it's after verb or verb+preposition...and then whether clause. But this one is really strange. Is it at all correct? Commented Jan 24, 2016 at 13:53
  • Fersher. It's the object of on here, and the PP is the complement of experts. No different from They disagree on whether .... Commented Jan 24, 2016 at 14:01
  • @StoneyB Structurally I agree. But syntactically? expert on A. "A" is a definite thing. whether adds doubt. Either this or that. I preferred or expected a verb like deciding after "expert on".. Commented Jan 24, 2016 at 14:07
  • @StoneyB I really agree with your first comment. I wonder why they categorize whether as a conjunction. Commented Jan 24, 2016 at 14:10

1 Answer 1


Whether is a correlative conjunction, which as that Wikipedia link says, work in pairs to join words and groups of words of equal weight in a sentence.

The specific pairing here is whether A or B, but in practice it often amounts to whether A or [not A], where that second "contrastive" element can be simply implicit, rather than explicitly specified.

In many contexts (I don't know whether you'll agree with me on this), you can treat whether and if as synonymous/interchangeable, but in both OP's cited examples whether is far more idiomatic. I think that's because in both cases the "referent" isn't exactly "A" (the only specified answer to a question). It's really the question/issue of whether A [is true or not]. In those contexts, whether works best.

To illustrate that last point, note the results from these Googlke Books searches (where rule means give a definitive answer/judgement in respect of a question or legal issue)...

We cannot rule on whether something is true / legal or not (347 hits)
We cannot rule on if it is true (0 hits)

...where if we change the verb to decide, you'll see from this NGram that in recent decades the "simpler" conjunction if has started to gain traction - because semantically, the verb decide tends to focus attention on one of the possible answers to a question, rather than the question itself.

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