sudanglo:I would prefer in this instance ŝi devigis min aĉeti ĝin.

Agreed. This is is a literal equivalent to Russian: ona zastavila menja kupit' ego.

I probably would even say ŝi min devigis aĉeti ĝin to distance the accusatives further away from one another, minimising the risk of ambiguity. SOV word order has extra clarity in this structure, especially if we modify the objects with adjectives or adverbs.

orthohawk:How about "Sxi igis, ke mi acxetu gxin"?

Can the complementizer "ke" be used with "igi"? I've not seen that before, but it seems understandable enough.

Meanwhile, "aĉetigi" risks being too complicated with two objects. I'm not able to immediately parse the correct meaning of mi manĝigos mian ĉevalon. Maybe this kind of verb+igi structure is best left to single-object phrases, e.g., La hontajxo lin rugxigis.

Tempodivalse:Meanwhile, "aĉetigi" risks being too complicated with two objects. I'm not able to immediately parse the correct meaning of mi manĝigos mian ĉevalon. Maybe this kind of verb+igi structure is best left to single-object phrases, e.g., La hontajxo lin rugxigis.

I use constructions like "ĉu vi helpos manĝigi la katon" with my 2-year-old very often, until now he didn't try to butcher our cat or the like.

Ah grilled cat with a lemon sauce. Yum Yum.

Tempodivalse:I'm not able to immediately parse the correct meaning of mi manĝigos mian ĉevalon.

I can see where there is some level of ambiguity, but I tend to read sentences like that as breaking down into two parts:

1) Mia ĉevalo manĝos. (My horse will eat.)
2) Mi kaŭzos tiun aferon okazi. (I will make that happen.)

That's the meaning that I automatically take away from that construction, and is what I would mean if I used it.

Tempodivalse:

orthohawk:How about "Sxi igis, ke mi acxetu gxin"?

Can the complementizer "ke" be used with "igi"? I've not seen that before, but it seems understandable enough.

That's how it would be constructed in Romance languages, and I believe in Slavic also (although in Russian the conjunction would be чтобы if I remember right....)

Can the complementizer "ke" be used with "igi"?

Seems possible. Just as you would say Ŝi postulis ke mi ĝin aĉetu.

Then, I think that there would be a nuanced difference between:

1. ŝi igis ke mi aĉetis ĝin
2. ŝi igis ke mi aĉetu ĝin

Still the best translation of She made me buy it would be ŝi devigis min aĉeti ĝin

sudanglo:

Can the complementizer "ke" be used with "igi"?

Seems possible. Just as you would say Ŝi postulis ke mi ĝin aĉetu.

Then, I think that there would be a nuanced difference between:

1. ŝi igis ke mi aĉetis ĝin
2. ŝi igis ke mi aĉetu ĝin

Still the best translation of She made me buy it would be ŝi devigis min aĉeti ĝin

I don't think there'd be a nuanced difference, I think only sentence #2 would be formally correct ('she made me buy it' ). So far as I understand Esperanto grammar, you'd have to use the -u (jussive/imperative) form in the subordinate clause there, not any form of the indicative. (And, of course, the -u form is tenseless, so the tense comes from the preceding indicative.) If you wanted specifically to say, for example, 'she had made me buy it', which is the pluperfect, you'd just use a compound form before the 'ke' clause, e.g. 'ŝi estis iginta ke mi aĉetu ĝin' (very literally, 'she was in a state of having caused that I should buy it'! But of course, much more naturally and properly, 'she had made me buy it' ) (as here).

As for being a complicated construction, yeah, it probably is, but I don't think it's so complicated that we couldn't get used to it through use -- as with anything, it all comes down to practice, as Kirilo81's clever two-year-old shows!

I think only sentence #2 would be formally correct

Why? Maybe inelegant, or not sufficiently explicit, but why not formally correct?

*-ig/. Suf. almetebla al ĉiaj rad-oj k esprimanta la efikon de ia kaŭzo, ne precizigante la manieron, kiel efikas tiu kaŭzo

Ŝi ne postulis tion, sed iel ŝi igis, ke mi aĉetis ĝin.

Surely, the nuance with the indicative is that that was the result or consequence, the -u form has the nuance of the imperative (the will of the other party)

Konsentite, ke kiam oni parolas pri personoj la verŝajna kaŭzo estas la insisto aŭ la postulo.

sudanglo:

I think only sentence #2 would be formally correct

Why? Maybe inelegant, or not sufficiently explicit, but why not formally correct?

*-ig/. Suf. almetebla al ĉiaj rad-oj k esprimanta la efikon de ia kaŭzo, ne precizigante la manieron, kiel efikas tiu kaŭzo

Ŝi ne postulis tion, sed iel ŝi igis, ke mi aĉetis ĝin.

Surely, the nuance with the indicative is that that was the result or consequence, the -u form has the nuance of the imperative (the will of the other party)

Konsentite, ke kiam oni parolas pri personoj la verŝajna kaŭzo estas la insisto aŭ la postulo.

Well, I just see it as equivalent to the English, 'he brought about that she [should] do this', which is the subjunctive, rather than, 'he brought about that she does this' (or much more likely, we'd just say, 'he caused her to do this'/'he made her do this', which would presumably be in Esperanto, li ŝin kaŭzis ĉi tion fari / li ŝin igis ĉi tion fari). To be fair, people maybe would say the latter nowadays, or maybe in the past too, but the formally correct version is the former. And the Esperanto equivalent of the subjunctive is the -u form. If you wanted the indicative for both verbs, so far as I can see, you'd have to say something like this: mi aĉetis ĝin kaj ŝi igis min [tiel fari]. But that sounds a bit round-the-houses (periphrastic). This page talks about the subjunctive in Esperanto, for example, and ends with a few paragraphs specifically about what we're talking about here, clauses introduced by 'ke'. As it says, it's a bit similar to how we have to use the -u form after 'por ke'.

I can definitely understand your argument that there isn't necessarily always an explicit wish, but I think the idea of causing something (even if there's technically no intention, like the wind causing someone to fall off a cliff) is 'grammatically volitive' enough that it'd still need to be there.

When you use 'ke' in your last sentence you're doing it to introduce indirect speech, which is something different: the indicative is generally used there, unless there's a specific reason to use another form. In other words, you're using the 'konsentite, ke' as equivalent to 'certas ke...', and a plain old indicative verb would naturally follow there. In fact, since you have 'konsentite' rather than some kind of verb like 'certas', I'd even say that it'd be better to get rid of the 'ke' altogether and just start with the 'kiam', which makes perfect sense.

Of course, no one needs to get too hung up about all this stuff though! Being understood is the most important thing, and whichever way you say it, it's definitely understandable. When I make mistakes, which I'm prone to, I'm usually understood too. Being too petty about grammar is for other languages, not Esperanto!

Y'know, maybe you're right, thinking about it. I'd be inclined to use the -u form, because it definitely seems a lot more natural to me like that, but I wouldn't say that's absolutely the only way. It's just the way I'd do it!