I am struggling to parse no matter what. (There are a couple questions on the site about the phrase no matter what but they revolve around how to use it.)
Is matter here a verb? Is it a noun?
If it is a verb, why does it not take an auxiliary verb?
No matter appears in NOAD as its own unit:
no matter
[ with clause ] regardless of: no matter what the government calls them, they are cuts.
it is of no importance: “No matter, I'll go myself.”
In the briefer phrase no matter (e.g. "If you don't want to go, no matter, we will stay put") it reads easily enough as a noun: there is no problem or nothing to consider.
matter, n
• an affair or situation under consideration
• a reason for distress or a problem (NOAD)
The what brings confusion, whether it is final or introduces the rest of a clause ("No matter what" vs. "No matter what comes next"). In "I won't believe you, no matter what you say" it doesn't really make sense to make matter a noun.
Perhaps a useless exercise, we can expand it with potential synonyms:
I won't believe you, no problem what you say.I won't believe you, no reason for distress what you say.I won't believe you, no substance what you say.- I won't believe you, no consideration what you say.
I leave #4 unstruck because it makes the most sense but, I find, not enough. This exercise is perhaps unhelpful because maybe another synonym could be used, or a perhaps a preposition could save the day, but I hope it serves my point.
So is matter a verb?
matter, v
be of importance; have significance (NOAD)
Before trying to defend matter's role as a verb we already see it functioning quite strangely: generally English requires an auxiliary verb for negating verbs. Is this my reason for confusion?
When what introduces the rest of a clause this more or less solves the matter:
⇒ "I won't believe you; it doesn't matter what you say"
but it remains murky when there is nothing to follow to the what:
⇒ "I won't believe you; it doesn't matter what
by no means provides the same sense of disregard and, besides, there isn't really a subject.
Best Answer
"No matter" is an idiom with the form of a noun phrase that takes a subordinate interrogative clause as complement.
Subordinate interrogatives can be reduced by ellipsis to just an interrogative phrase like "what" if the rest of the clause is recoverable anaphorically. The whole NP "no matter what" then functions as an adjunct in clause structure.
The reduced interrogative "what" is a kind of conditional clause called an 'exhaustive conditional'. Things become clearer if the reduced conditional clause is expanded to an equivalent full clause as in, for example, He'll complain, no matter what you ask him to do, where we understand that he'll complain if you ask him to peel the potatoes and he'll complain if you ask him to set the table and so on: he'll complain for every possible x where you ask him to do x.
The interrogative clause, reduced or in full, thus expresses a question whose answers define an exhaustive set of conditions, hence the name 'exhaustive conditional'.