“This was a nice evening” is also difficult to characterize as not caring about which evening it is. As are books titled “An Introduction to XYZ”, where both the authors and the readers will probably care about the specific book.
I'm going to a bank, a shop, a dentist - I've found a new one and I may well be about to describe it to you.
"A nice evening" - there have been ones before, there hopefully will be again, this was one of them.
Here it only sounds OK if you make the adjective stronger ("this was the nicest evening", though you'd probably avoid "nice" in this case and go with "best", "most amazing"...), or drop the adjective altogether ("this was the evening").
So nuance is that you might have many nice evenings, with this being one of — but what if you do not, and all are actually terrible except for this one? I guess with proper pronounciation of "THE nice", it can still work (we already talked about nice evenings and not-nice ones, so it'd be "this was the nice one"), but it'd be pretty awkward.
However it can makes sense if the surrounding context supports the idea of only one nice evening.
Grammar rules are generally about the surrounding context which allow us to leave out superfluous or repeated information and still be understood. Things sound strange when that missing information can’t be deduced from context.
Edit: Here's a frustrating HN thread where someone tried to claim it makes sense, but it turned out his argument hinged on "well obviously all native English speakers regularly go to some store, right?" Screw the homebound.
I think the usage falls into this group: "The first group consists of nouns which refer to shared knowledge of the situation or context...",
When you're talking to people you live with it is true that they know which store you are going to. Friends and neighbours would have also have known up to fairly recently, when people still mostly walked for groceries and such to the few small stores nearby and made friends with people who lived close.
So, I'd say it's a bit of a colloquial hold over from walking times and construction taking a listener into confidence.
But again, people use this even when I have no reason to know which store they went to.
I’m not necessarily saying they should stop doing this, but it’s clearly not the usual kind of definiteness implied but the use of “the”.
A prescriptivist pedant might insist that this is incorrect, and they should instead say "I need to go to a store", but in my judgment as a native speaker, the version with "the" is more idiomatic, and the version with "a" sounds stilted.
To repeat another part of my initial post, it's like the use of "the" in "the bigger they are, the harder they fall". It's clearly a different usage/meaning/sense of "the" -- in fact, most other languages use a different word for that sense. (German uses je ... desto.) It would be very dubious to explain all uses of "the" as "oh its when the noun has definiteness". It wouldn't cover that case, and it wouldn't cover (the typical use of) "I went to the store".
Some of the statements (by other people) in this conversation are wrong, based on applying a school-style oversimplified explanation that doesn't really match English usage.
How can this be in your example? When I am saying "I went to the store", I am really saying "There are a group of locations that I could have gone. E.G., the car dealership, the bank, the museum, the store, or the office. I went to the store".
Well, that would work for many uses of the, but it's definitely not a correct explanation here. If I have no idea where the bank is, I'll still describe myself as going to "the bank". I could tell you that "I'm going to the bank", go out and get in my car, and then look up where a convenient bank is. This has to be viewed as idiomatic, or as "the bank" being an abstract task-based location rather than a concrete physical location.
"I have the son" sounds odd, even if there is only 1 son on your mind.
"Our house has a pool" for example. There is a very specific pool being referred to, but it's sufficiently indirect that "the" would never be used here without radically changing sentence meaning.
It's like saying "our house has a roof" — very similar, but nobody really cares about the roof, the focus remains on the house.
If you refer to that same pool without introducing it, it will still be marked for definiteness - compare my pool, my house's pool, or the pool at my house. But your example sentence doesn't work that way.
(Note that the three phrases I listed are all bare noun phrases that can't stand as sentences. Note also that if you used one of those phrases when your listener wasn't already aware that you had a pool, they might feel that you "moved too fast" in the conversation, assuming that they knew about your pool when they didn't.)
Because you are referring to a specific one of each, even if a listener doesn’t necessarily know which specific one, they know that you know.
In the case of your example the listener assumes you mean whichever specific dentist you are currently seeing. That fact that you may choose one randomly each time is an exception.
the doctor, the cinema, the dentist, etc imply there's one family connection you use, or it's the local place everybody uses. "The" specifies "the one" everybody uses.
I'm guessing saying 'a' doctor would've looked at the role as an abstract concept. "To be a doctor would be wonderful" vs "to be the doctor would be wonderful".
I guess it's language clinging on to a sense of community.
So I feel the rule isn't always taken literally, but the vs a is selected based on whether something is up for consideration/substitution rather than something that's well defined and specified.
And he may be saying "a" about the word "nice" instead of about the word "evening".
Note: This is just my opinion and an attempt at trying to make sense of it. Purely subjective take as I usually refrain from making purely opinion based arguments.
All of the above is in my opinion, but I never state that and assume a good faith reader will take it as such (here for demonstration purposes only :)).
So in short, thanks for your opinion, and I agree this is the largely the basis for choosing between an indefinite and definite article, also opening them up to inquiry ("I am going to the store" — "oh, which one?"; compare to "I am going to a store" — "what are you getting?").
For context, extensive coding over two decades has ingrained in me the habit of explicitly disambiguating my statements of machine-executable logic expressed in natural language from personal guesswork and opinions.
I should integrate your suggestion and try not to explicitly qualify my guesswork. Using passively implied qualifiers in the structure of my opinion pieces would be a step in the right direction.
"Chocolate ice-cream is the best" is very clearly not an (attempt at) objective statement and needs no qualifiers. Only if the reader really wants to be malicious, they can question even that too: what do you base that on? how many ice-cream types have you tried? is there a study confirming preferred taste among a large population? is it cultural and has that been tested? ...
"In my opinion, based on roughly 60 ice-cream flavors I have tried in my life, and having tried chocolate flavor in at least 50 different places, I find that the taste of chocolate ice-cream on average is the best tasting ice-cream regardless of my mood, fullness or place of production and variety of 'chocolate' used" makes for a very boring conversation — except sometimes when you are making a go at it :)