whether...A or B vs. whether A, or whether B

(1) *I'm buying it whether I can afford it.

(2) I'm buying it whether I can afford it or not.

(3) I'm buying it whether I can afford it, or whether I have to take out a loan.

I think (1) doesn't work, because it doesn't contain an or-coordination, as in (2), which works fine.

How about (3)?

Can the or-coordination reside outside the whether-clause, as in (3)?

EDIT

I wouldn't use (3) myself; I would say (4) instead:

(4) I'm buying it whether I can afford it or (I) have to take out a loan.

(This doesn't mean that I don't think (3) works. All it means is that I'm not too familiar with constructions like (3), if it does work.)

But I've seen constructions similar to (3). So I'd like to know whether constructions like (3) are well formed.

Research I've done

I've looked up a few grammar books including CGEL by Pullum, but to no avail.

EDIT

Specifically, I'd like to know how common constructions like (3) are compared to its counterpart like (4), and whether the former is a well-formed alternant of the latter simply when the whether-clause is too long and/or complicated to be written in a single clause.

Further clarification and an attested example

The question is not about the general use of 'whether', but only about the use of 'whether' in an exhaustive conditional construction where the whether-clause is functioning as an adjunct of the matrix clause.

At the time of this writing, I've received two answers, both of which claim that (3) doesn't work. But I've just found an example similar to (3):

(5) And I want to assure you that this President is going to continue to work with members of Congress, like Congressman Andy Harris, to make sure that you have the resources and the support that you need to accomplish your mission — whether that be saving people from human trafficking, whether it be sparing families the scourge of narcotics, drug abuse, addiction, and overdose, or whether it be stopping the violence of MS-13 and other gangs that are flowing into our country.

This is from "Remarks by Vice President Pence in Meeting with ICE Baltimore Field Office Leadership".

The difference between (3) and (5) is that (5) has a more complex construction of 'whether A, whether B, or whether C', and that the verb be in (5) is in the present subjunctive form.

Hopefully final edit

In response to the claim that the whether-clauses in (5) are not mutually exclusive, here's another example from "Remarks by Vice President Pence in Press Gaggle":

(5') So, we’ll — all these steps are designed to demonstrate this is a President who embraces his role as leader of the free world. But with regard to Venezuela — whether it be Russia or whether it be Iran — the President’s message is very clear: Russia and Iran have no business in Venezuela. They should step aside and allow the people of Venezuela to restore their democracy and their freedom.

I'm sure 'it being Russia' and 'it being Iran' are mutually exclusive.

Solution 1:

The repetition of whether in interrogative content clauses (where whether could be replaced by if) is unnecessary but grammatical. Fowler's Modern English Usage (p696) has an example:

• I cannot remember whether they were lowered into the street or whether there was a window opening out at the back.

Fowler states:

"Whether is often repeated as a clearer pointer than a bare or to an alternative that forms a separate sentence."

However, in the sentence I'm buying it whether I can afford it, or whether I have to take out a loan we are dealing with what A Comprehensive Grammar Of The English Language (p1100) calls concessive conditional clauses, not interrogative content clauses. And the whether means regardless of whether or no matter whether, not if.

But in its explanation and exemplification of concessive conditional clauses the CaGEL explicitly refers back to an example similar to Fowler's in its discussion of interrogative clauses:

• I can't find out whether the flight has been delayed or whether it has been canceled.

This is the passage in question:

"The correlative sequence whether...or (whether) is an alternative condition in that logically it combines the conditional meaning of if with the disjunctive meaning of either...or. It is thus a means of coordinating two subordinate clauses. If the second unit is a full clause, whether may be repeated as in [the flight sentence above]:

Whether Martin pays for the broken vase or (whether) he replaces it with a new vase, I'm not inviting him again."

So, the CaGEL would regard the OP's sentence as 'well-formed', and following Fowler we could say that the repetition of whether serves to give the or clause slightly greater emphasis than it would have without it.

And in the Pence example, the repetition of whether separates and gives equal prominence to each of the three fairly long clauses headed by it.

Solution 2:

For usage, I suggest you look in a dictionary that has example sentences, not a grammar book.

I find that Oxford gives lots of examples, so that will be my starting point.

1 Expressing a doubt or choice between alternatives.

‘he seemed undecided whether to go or stay’

‘it is still not clear whether or not he realizes’

1.1 Expressing an enquiry or investigation (often used in indirect questions)

‘I'll see whether she's at home’

1.2 Indicating that a statement applies whichever of the alternatives mentioned is the case.

‘I'm going whether you like it or not’

‘The same position applies if it is not known whether a deportation order has been made or not.’

Phrases

whether or no

1 Whether or not.

‘the only issue arising would be whether or no the publication was defamatory’

2 In any case.

‘God help us, whether or no!’

Now to the feedback on your four proposals.

(1) I'm buying it whether I can afford it. This structure doesn't appear in any of the examples, so you are right, we're going to have to nix this one. Here's what would work:

I'm not sure whether I can afford it.

(2) I'm buying it whether I can afford it or not. From the Oxford examples, we see that this is fine (see 1.2). Note that it is also possible, and perhaps more common, to swap the order, which would result in

I'm buying it whether or not I can afford it (see 1.1).

(3) I'm buying it whether I can afford it, or whether I have to take out a loan. This one doesn't appear in any of the Oxford examples, so I checked Cambridge. It has

I didn’t know whether he was too busy or (whether) he just didn’t want to see me.

But this example is from the other meaning of whether -- "Expressing a doubt or choice between alternatives (Oxford)," "used especially in reporting questions and expressing doubts (Cambridge)." Your (3) is the meaning "Indicating that a statement applies whichever of the alternatives mentioned is the case (Oxford)," "used to introduce two or more possibilities (Cambridge)."

So (3) doesn't work as written.

(4) I'm buying it whether I can afford it or (I) have to take out a loan. This is fine as long as you don't omit the I in the parentheses.

Responding to additional material in question:

(5a) (with some simplification) This President is going to make sure that you have resources you need to accomplish your mission — whether that be saving people from human trafficking, whether it be sparing families the scourge of narcotics, or whether it be stopping the violence of MS-13 and other gangs that are flowing into our country.

(5b) I am absolutely convinced that segregation is on its deathbed, and those who represent it, whether they be in the United States or whether they be in London, England, the system is on its deathbed (MLK).

The subjunctive is a red herring. It doesn't change things.

The extra whethers in 5a and 5b aren't needed. I believe they serve a rhetorical purpose and this is an example of pleonasm, defined in Merriam-Webster as

the use of more words than those necessary to denote mere sense.

Pleonasm, which stems via Late Latin from the Greek verb pleonazein ("to be excessive"), is a fancy word for "redundancy." It's related to our words "plus" and "plenty," and ultimately it goes back to the Greek word for "more," which is "pleōn." Pleonasm is commonly considered a fault of style, but it can also serve a useful function. "Extra" words can sometimes be helpful to a speaker or writer in getting a message across, adding emphasis, or simply adding an appealing sound and rhythm to a phrase