Can you choose a dialect of a language instead of the whole language?

Question

PCs can speak languages. Generally, they are given Common and one other than fits their race (e.g. for a dwarf: "You can speak, read and write Common and Dwarvish", from PHB, pg. 20). There are a few races who are simply given a choice of any language, such as humans or tabaxi, and others who get a free langauge, such as half-elves or high elves. Furthermore, some backgrounds allow you to learn one or two extra languages.

For the cases where you get to pick a language, must you pick the whole language, or can you choose to know only one dialect of that language? In particular, I'm thinking of Primordial and its dialects Aquan, Auran, Ignan and Terran. From the PHB, pg. 123:

Some of these languages are actually families of languages with many dialects. For example, the Primordial language includes the Auran, Aquan, Ignan, and Terran dialects, one for each of the four elemental planes. Creatures that speak different dialects of the same language can communicate with one another.

If a PC has an in-character reason why they would only have learnt one dialect, such as a half-elf who is half-sea elf and was raised by the sea elves and thus learned only Aquan, or a human who spent some time among Azer or Salamanders or something and thus speaks Ignan, these characters would have no exposure to the other dialects, so picking Primordial wouldn't make sense.

There is some precedence for PCs only speaking certain dialects, since there are certain playable races, such as the Kenku (Volo's Guide to Monsters, pg. 111) and Aarakocra (Elemental Evil Player's Companion, pg. 5) who both speak Auran, not Primordial; there's also the aforementioned sea elves (Mordenkainen's Tome of Foes, pg. 62) who speak Aquan. On the other hand, Genasi (Elemental Evil Player's Companion, pg. 9) all speak Primordial, regardless of which subrace they are (even though it could be argued that it would make sense for them to only speak the dialect that matches their element).

When a player picks a language for their PC, can they choose just a single dialect of a language instead of the whole language, such as Primordial?

Answer 1

So, this player character knows Aquan, and someone wants to speak Auran to them.

As Aquan and Auran are both dialects of Primordial, that means they are mutually intelligible. That is, someone who knows Aquan can understand Auran, and someone who knows Auran can understand Aquan. The PC can talk in Aquan, and the NPC can talk in Auran, and both can understand one another.

It is not possible, according to the book, for someone to understand Aquan but not understand Auran. The languages are just too similar to one another for that to be plausible. It’s like someone speaking African-American Vernacular English to someone speaking Indian English—the languages sound pretty different, and they use some different structures and grammar, but they’re close enough that it’s hard to imagine that these two wouldn’t be able to understand one another. Have a try at reading the Scots-language Wikipedia article on the Scots language, for example: you probably can get through it, because Scots and English are mutually intelligible. Auran and Aquan are at least that close, according to the books.

This is in contrast to other “dialects,” such as those of Chinese, which are not mutually intelligible: someone who speaks Cantonese has no particular understanding of Mandarin, and vice versa.

So no, the player cannot choose to know only Aquan; there’s no such thing as knowing that without understanding the other dialects. Moreover, the language choice option covers the entire language family—that is, they don’t just understand all of the Primordial dialects, but they can speak and write in them too. To choose not to have that aptitude would be to diminish the value of the language choice, which obviously isn’t the end of the world, but as a DM I’d be somewhat leery of it, at least in a game where I expected languages to matter in the first place, and in any event the official rules don’t really allow it.

But more importantly, allowing the player to only really “know” Aquan (and therefore be able to understand the other dialects but perhaps not be able to speak or write them) is simply unnecessary. Nothing stops the player from freely choosing how to characterize this choice for their character: they can easily say, sure, my character knows Auran and Ignan and Terran and Primordial too, but they speak all of those with an Aquan accent, and will sometimes use Aquan-specific idiom and slang inappropriately in those languages, because Aquan is really their languages. The advantage of this, over saying they only know Aquan, is that if it ever comes up, the character can get by in those languages—which is usually a good thing, because “oops, no one knows that language” tends to be a bit of a buzzkill interruption in the game more than something interesting (and in a game where it was interesting, I’d be more concerned about the self-nerf since apparently languages matter here).

Characters of races or what have you that specify they know only Aquan or whatever would have a lesser degree of understanding, and would probably struggle mightily to express themselves in any of the other dialects.

But in both cases (only “knowing” Aquan vs. knowing Primordial but with an Aquan characterization), there may be nuances that get missed, cultural details that aren’t apparent from the mere meaning of words, and so on, but that has as much to do with the cultures each is coming from as it is to do with the actual language used. They also might have to speak more slowly and carefully, and possibly dumb down their language to avoid dialect-specific or culture-specific idiom or grammatical structures. Personally, I would not typically want to get mechanics involved in this—disadvantage on all checks seems much too harsh to me, for example—but keep this a matter of roleplaying.

Answer 2

You pick the language, the dialect is more of a flavor

It's Flavor, not function

Given that the Basic Rules state:

Creatures that speak different dialects of the same language can communicate with one another.

There really isn't much of a functional difference between knowing Primordial or knowing one dialect and communicating with someone who speaks another.

This also suggests that when picking the language, you are picking Primordial and then saying you speak with the Aquan dialect.

This is supported by that if you know Primordial, you know all dialects.

Answer 3

@KRyan's answer is correct with regards to dialects. Yes, it's like that in real life too. I speak Mexican Spanish. If I need to speak to someone in Spain, I just speak more slowly, take my time, and occasionally ask them if they can phrase something another way. It works 99% of the time. Occasionally I speak with someone with a more Argentinian twang. They sound a little weird from my perspective (why are they using a phoneme from French that I was never taught to use in Spanish?), but I can still communicate.

Consider @NautArch's mention of flavor. This, I believe, is one of the biggest benefits of dialects and related linguistic features such as accents. The dialects are primarily a social distinction. Imagine you are in Washington, DC and you come upon three English-speaking people on the train: one with a thick Brooklyn accent, one with a "Hahvahd" accent, and one speaking, like, totally like a California Valley Girl (like, gag me with a spoon!). Are you likely to perceive each of these the same way? You might say yes, but instinctively you may not. Each of these ways of speaking carries stereotypes that affect the way we are perceived. A Brooklyn accent carries perceptions of lower class and perhaps even stereotypical New York City rudeness. A Harvard accent implies (but does not prove) erudition and education. A Valley Girl accent implies wealth and consumerism. Are these stereotypes accurate 100% of the time? Probably not, but that does not mean that the stereotypes somehow don't really exist or don't affect anyone!

Going back to DnD, suppose your character speaks Aquan. Sure, he can understand and communicate with Auran speakers. Does that mean that he will automatically be accepted into Auran-speaking society? Maybe he will still be seen as some "foreigner who talks funny", and, in any event, "isn't a member of the club". He may face discrimination, fear, or rejection. This is a social barrier that perhaps could be ameliorated by taking Auran as an additional language.

Going back to the real world, these dialect courses do exist. You can take a course in Standard US English for UK English speakers. You can take a course in Danish for Norwegian speakers. Hindi speakers can learn the Arabic script for Urdu, build some vocabulary, and start speaking halfway-decent Urdu in a month. These courses aren't truly necessary for basic comprehension. They are useful for demonstrating good faith and cultural respect.