IainDonnchaidh wrote:The do dh' / a dh' is not the result of this elusive infinitive that people keep trying to conjur up but simply a directional preposition when there is a verb of motion involved (a' dol, thàinig etc) i.e. I am doing towards drinking (in Gaelic anyway).
Hmmm ... I was simply following the regular verb conjugation guide in my dictionary
Tha mi a' dol dham taigh-osda uisge-beatha a dh'òl.
Tha mi a' dol dhan bùth biadh a cheannich.
No no, that's quite right.
The difference here is "dol".
As Akerbeltz says, this "a" is really "do" -- a preposition of motion.
"iarr"/"iarraidh" is not a verb of motion, so it would be strange to use a preposition of motion, would it not?
Let's wind it back.
Gaelic is all about nouns, right? There's a reason Akerbeltz gets all het up about the word "infinitive" -- it hides the truth (and I finally understand why!)
So let's start with just plain nouns in English:
I want the house.
I'm going to the house.
Notice how with "want" there is no "to", but with "going" there is? Well that's obvious -- it's English and we all speak it well enough here!
Let's put them into Gaelic.
Tha mi ag iarraidh an taighe.
Tha mi a' dol dhan taigh. (= Tha mi a' dol do an taigh)
But a verbal noun is just like any other noun, so we can just replace "taigh" with any verbal noun:
Tha mi ag iarraidh òl.
Tha mi a' dol a dh'òl. (= Tha mi a' dol do dh'òl)
Tha mi ag iarraidh tighinn.
Tha mi a' dol a thighinn.
Gaelic goes to the event described by the verbal noun:
They're coming to take me away = They're coming to the taking away of me
They want to take me away = They want the taking away of me (no to)
The confusion here is that English seems to have taken the "to" from "going to" and generalised it to be a marker of the infinitive, so we as English speakers think about "wanting to" and "going to" as being the same construction, when they're not*; but if you stop thinking of verbal nouns as verbs and keep thinking of them as nouns, then obviously there's no "to" after "want"
*(The distinction occurs in other languages, too. Did you do any Spanish at school? Compare "quiero hacer algo" with "voy a hacer algo". Teachers might tell you that "a" isn't "to", but it looks like a duck and it quacks like a duck...!)