If only, with would in two clauses (if only, would + infinitive, would + infinitive )

In Swan's Practical English Usage section 265 on (if only) item (b) would + infinitive (without to) to talk about the future, he gives the following example:

If only it would stop raining, we could go out

I was wondering if we could use (would) in the main clause too. I googled up but all the pages I have seen aren't any different than Swan's. Here's an example I made it up:

If only he would sell me his car this week, I would give him \$1000 more.

The following sentence does not use "if only..." idiomatically, IMO.

If only he would sell me his car this week, I would give him \$1000 more.

In an if-only statement, the independent (main) clause expresses something that becomes possible when the if-only condition is true. The thing made possible is something that is wished for.

In your example, "I would give him \$1000 more" is not something that is made possible and wished for. It is a quid-pro-quo.

If he would sell me his car this week, I would give him \$1000 more.

But this following sentence would be idiomatic if his selling you the car would allow you to drive to a gig where you could earn the additional money, for example; if you had a fleeting opportunity:

If only he would sell me his car this week, I could give him \$1000 more.

• There's nothing wrong with the "if only...would...would" sentence. The main clause of an "if-only" statement doesn't have to express possibility - it's no different from an "if" statement, except that it expresses a (frustrated) desire for the condition to be true. Putting "could" changes the meaning - using "could" would indeed imply that paying an extra \$1000 would become possible if the condition were satisfied; using "would" instead means that the speaker would be willing to pay extra in that case. Oct 21, 2014 at 20:47
• I agree with FumbleFingers that "unless the required condition is met, we can't take the action mentioned." In other words, the action expressed is impossible unless the condition is met. If only you noisy kids would play outside, I could take a nap. I don't see anything like that in I would give him \$1000 more" "Would" expresses volition: it lies within the speaker's power to pay him \$1000 more for the car whether he sells him the car this week or next. "Oh, how I wish he would sell me the car this week, for I would pay him \$1000 more for it if he did..." doesn't make good sense, IMO.
– TimR
Oct 21, 2014 at 21:05
• I certainly agree that "would" expresses volition. But I'm not sure I see any difference between "... I would meet his price" versus "...I would give him \$1000 more": grammatically they're identical, and in meaning they're very close (i.e. I'd be prepared to pay extra, if only he'd sell this week). Oct 21, 2014 at 22:33
• @FumbleFingers: No disagreement that that's what 'could' means in the examples. But the question was "can you use 'would' in this context", to which I'd answer "yes, but the meaning is different" :-). @ learner: How about: "If only he would let me in the kitchen, I would prepare dinner every night." Oct 22, 2014 at 7:55
• @TRomano: That's probably a clearer summary of the distinction than any other attempts we've been making in these comments. I originally thought OP was just asking a general question about using would/could to express a potential outcome if some neutrally-viewed condition obtains. But in the final analysis, if that condition is introduced by if only, it's no longer neutral - it becomes a desired condition (that the speaker wants, because he favours the outcome which will then arise/be possible). It's an incisive and subtle question, that I forgot to upvote until now. Oct 22, 2014 at 14:00

Using could in such contexts emphasises the fact that unless the required condition X is met, we can't take the action specified. Thus it's usually If X, I could [do what I want], or ...would [do what you want].

So by implication, using could in OP's second example would carry a fairly strong implication that I actually want to give him another \$1000 - and the only thing stopping me doing what I want is he hasn't sold me the car this week (it's also implied that he's reluctant to sell, perhaps deliberately thwarting me).

By further implication, the use of if only in OP's example makes the second would rather less likely to a native speaker (we'd normally use could there, reflecting the "frustrated desire" associations of if only).

TL;DR: OP's first cited usage is perfectly normal. The second is valid, but slightly unusual because only implies something the speaker wants to be true - so it's more likely to be followed by some potential gain (from the speaker's perspective) that would result from X being true, rather than some concession he would be prepared to make if X were to be true (in some contexts, in order to make X be true).

• I'm not sure about that - the "would...would" example seems absolutely fine to me (as a native speaker) - with a slight difference in meaning; as you note the "could" emphasises that the extra \$1000 becomes possible if the condition holds; with "would" it's more about becoming willing to pay it if the condition were satisfied... Oct 21, 2014 at 20:55
• @psmears: I did try to "hedge" that point quite a bit (it's only a further implication making it rather less likely than what we'd normally use! :). Maybe the preceding "only" doesn't imply anything relevant to you, but to me it suggests greater frustration at not being able to do what you want, rather than a simple statement of what would happen if the condition obtained. I'll just add that whenever someone says something starting with "If only...", they might well be told "If wishes were horses, beggars would ride". Oh - and welcome to ELL! :) Oct 22, 2014 at 1:46
• The "only" certainly implies frustration at not getting what one wants - but (in general) a "would" in the result clause then goes on to describe what one would be prepared to give in order to get that (as opposed to "could", which describes what you're being restrained from doing)! And thank you :-) Oct 22, 2014 at 7:45
• @psmears: These comments are actually convincing me that only in OP's second example is more significant than I originally thought. Your distinction re would cede [if condition X were met] as opposed to could gain [if X] is perfectly true. But to a considerable extent, only conflicts with the former because it implies the speaker actually wants that only [remaining?] condition to be met. The only justifiable change I can see is I didn't need to hedge my first statement so much... Oct 22, 2014 at 12:53

Both of the original poster's examples are grammatically correct.

The second example (with "would" in both clauses) is a bit confusing. Most of the confusion is due to how long the sentence is. It can be shortened to:

If he sells me his car this week, I will give him \$1,000 more.