I ought to know who I am

Here's a scene from Alice in Wonderland (2010)

I'm particularly interested in the following passage:

Caterpillar: Who are you?
Alice: I'm Alice.
Caterpillar: We shall see.
Alice: What do you mean by that? I ought to know who I am.
Caterpillar: Yes, you ought, stupid girl.

1) Does Caterpillar's ought mean something different than Alice's ought? What is it implying?
2) Would any other modals (must/should/have to/need) instead of ought fit this dialogue? (I think they wouldn't.)

Alexey86 said:

1) Does Caterpillar's ought mean something different than Alice's ought? What is it implying?

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When Alice says "ought to know," she is saying it is obvious she knows who she is because she has direct personal experience. She feels a little insulted or at least surprised that she was challenged on who she is.

When Caterpillar says "ought," he means he agrees that Alice should know, and the fact that she nevertheless doesn’t shows how stupid, naïve, or ill-informed she is. His “stupid girl” addendum makes this meaning even clearer. What exactly he means by suggesting she might not in fact be Alice is not clear, which makes this a fun, open question that the audience can guess at or that will be explained/revealed later in the book/movie.

Alexey86 said:

2) Would any other modals (must/should/have to/need) instead of ought fit in with this dialogue? (I think they wouldn't.)

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As an AmE speaker, I think “should” would work 90% as well for this dialog (the other modals you suggested don't work). Alice could say "should" instead of "ought to" and the meaning would be 100% the same, but it would change something interesting about Caterpillar's reply (see below). In Caterpillar's reply, ought works better than should for two subtle reasons.

1. "You should" on it's own is a common sentence/reply, but using "you ought" without adding "to" is not common. Whether he used "should" or "ought," he'd be reversing her meaning. But because of the unusualness of how Caterpillar leaves out "to," he makes it sound like he is going out of his way to not only disagree with her, but also to intentionally mirror her language and thereby mock her while doing so.

2. To my ear, if Caterpillar used "should" instead of "ought," his reply would lose a bit of gravitas and thereby lose some of the implication that there is an important reason she should know or an important thing that will later be revealed about Alice.

I find this short dialog to be exceptionally well written. It manages to embed subtlety, character, mystery, whimsicality, and disorientation in just a few simple words. "We shall see" is another great reply in this exchange.

slevlife said:

As an AmE speaker, I think “should” would work 90% as well for this dialog (the other modals you suggested don't work). Alice could say "should" instead of "ought to" and the meaning would be 100% the same

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When someone says I should do that, the implication is I haven't done that yet. So, wouldn't I should know who I am imply that Alice doesn't know who she is from her own point of view? If so, it would contradict her fist line and the fact that she's quite sure about who she is at the moment of speaking.
Could it be that I ought to know has an implication that I should know doesn't, i.e. to know who you are is something that everyone is supposed to know according to common sense and social expectations?

No. When talking about knowing something (depending on the context and supporting words) “I should know” and “I ought to know” have the same meaning, which is that it is obvious/evident based on who the speaker is or their experience.

Consider a sentence using "I should know" that has a very different meaning. In this and all following sentences, I'm using "should" as a stand-in for either "should" or "ought to."

”I should know how to get there by now.”

“By now” makes it clear the speaker doesn’t know how to get there yet, despite having been there multiple times in the past.

Contrast that with a sentence that uses the meaning we've been discussing in this thread:

“I should know; I’ve been there a hundred times.”

Here, the speaker knows how to get there, and is explaining why it is obvious (to the speaker) that they know.

And then there are some sentences where stressing the word should or know (via tone or an intensifier) could cause a switch between these meanings:

”I should know how to get there.”

This is ambiguous, but by intensifying either should or know (e.g., via “I really should know,” “I should really know,” or just by stressing should or know in speech), it would make it clearer that you don’t know yet. If you wanted the other meaning to be clear, you’d probably need to add a follow-up sentence (e.g., “After all, I've lived there for 20 years.”)

This is how I read it, which is very similar I think to how slevlife reads it:

Alice: I ought to know who I am = It is self-evident that I know who I am. She's stating a logical truth.

Caterpillar: Yes, you ought, stupid girl. = You don't know who you are. The caterpillar is criticising the use of logic in the previous utterance.

I think the caterpillar is subtly making a distinction often made in philosophy between an 'is' and an 'ought', where an 'is' is a proposition that is the case and an 'ought' is a proposition that somebody thinks should be the case. In other words, the caterpillar is saying that for one's own benefit one should know who one is, but such knowledge of self is something that must be worked on.

These are two deliberately contrasted 'oughts'.

slevlife said:

No. When talking about knowing something (depending on the context and supporting words) “I should know” and “I ought to know” have the same meaning, which is that it is obvious/evident because the speaker has direct personal experience.

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The question is whether it's all about Alice's personal or social experience in the first place. She equals her "I" or "self" to her name (Caterpillar didn't say What's your name?). We get our names from our social environment (parents). And one of the first things we learn is to respond to our names, which is a common social rule or expectation about good behavior. And kids are so used to it that they take it for granted that "I" = "my name" (external social label). That's why it seems obvious for Alice that she knows for sure who she is, and why she is surprised and even feels offended when Caterpillar questions that.
Doesn't ought to fit better such a context?

jutfrank said:

Alice: I ought to know who I am = It is self-evident that I know who I am. She's stating a logical truth.

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Doesn't it seem to you that it's not only about bare logic? She's also implying I'm a good girl (= good member of society) because I know what any good girl is expected to know.

jutfrank said:

This is how I read it, which is very similar I think to how slevlife reads it

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jutfrank, I agree with or at least accept your reading. To whatever extent our readings differ, the differences likely result from the intentional ambiguity.

Alexey86 said:

The question is whether it's all about Alice's personal or social experience in the first place. [...] Doesn't ought to fit better such a context?

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I disagree that using "should" in Alice's statement would change anything about the meaning. She's using a common phrase, and should is equivalent for the phrase (not to mention more common, at least in AmE).

Side note: In my explanation that the phrase is about direct personal experience, I was trying to give a more general definition that explains how the expression "I should know" / "I ought to know" can be interpreted in many contexts. jutfrank's explanation that she means "It is self-evident that I know who I am" is a more precise/clear definition for this specific context.

Alexey86 said:

Doesn't it seem to you that it's not only about bare logic? She's also implying I'm a good girl (= good member of society) because I know what any good girl is expected to know.

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I think you're overreading into her words. Caterpillar is the one being clever with language; not her.

Alice's line is perfectly normal and natural. Its usage is common in BrE.

Helen: My mum loves aubergines.
Sam (friend): No, she doesn't. She hates them.
Helen: Excuse me but I should know! She's my mother! (or "I ought to know! She's my mother!")
Sam: Fair enough.

As slevlife said, Caterpillar is the one playing with language to make a little joke. It's not quite a pun but it is meant to be humorous.

slevlife said:

I think you're overreading into her words. Caterpillar is the one being clever with language; not her.

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I see nothing clever in that implication. We always imply something and kids are no exception.

I made no comment on whether his implication was clever. I said he was being clever with language. That's similar to emsr2d2's phrase "playing with language."

slevlife said:

I made no comment on whether his implication was clever. I said he was being clever with language. That's similar to emsr2d2's phrase "playing with language."

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Sorry, maybe I got you wrong. You said, Caterpillar is the one being clever with language; not her as if the implication I saw in Alice's reply somehow made her the clever one. To which I replied that there's nothing clever about that implication.

Um, I'll invert my last comment to focus on Alice, in case that helps. By saying Alice is not being clever with language, I am not talking about whether she is clever or something about her implication (that I don't see) is clever. I am saying there is nothing non-obvious to read into her words. She is using language plainly.

Alexey86 said:

Doesn't it seem to you that it's not only about bare logic? She's also implying I'm a good girl (= good member of society) because I know what any good girl is expected to know.

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No, it doesn't.

Throughout the whole novel, Lewis Carroll finds various ways to play with our notions of logic and meaning. This is just one such case.

slevlife said:

I am saying there is nothing non-obvious to read into her words. She is using language plainly.

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There is no contradiction between plain language and implications. It's just the nature of human language and psychology: every utterance has a non-obvious part even if we just state facts. But I think it's too big of a topic to start it here.

jutfrank said:

No, it doesn't.

Throughout the whole novel, Lewis Carroll finds various ways to play with our notions of logic and meaning. This is just one such case.

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It's worth mentioning the original dialog was changed by the screenwriters. But that's not the point. I see no contradiction between playing with logic and meaning, and the possibility of the implication I suggested.

Alexey86 said:

I see no contradiction between playing with logic and meaning, and the possibility of the implication I suggested.

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No, me neither. I guess I don't really get what your idea is. Could you try explaining it again? How are social expectations related?

Alexey86 said:

I see no contradiction between playing with logic and meaning, and the possibility of the implication I suggested.

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Agreed, there's no contradiction. But then, you didn't seem to know what the phrase meant, and wanted to disagree when the meaning was first explained. How likely is it that the implication you're finding in the phrase (that we're telling you is not there) was in fact intended or will be found by other people here?

Of course, it's possible that we haven't understood your explanation. jutfrank is nice to invite you to explain again. But I'm pretty skeptical. ;-)

It's important for our discussion that Alice in Wonderland takes place in the 19th century. The difference in use between should and ought was more distinct in those days. Let me refer you to Should and ought: the rise of individually oriented modality in American English by J. Myhill (https://ur.booksc.eu/book/40401903/88594c). The author draws a distinction between individual orientation (should) and group orientation (ought). What I stated in post #6 can be effectively boiled down to the latter.
Mr. Myhill, however, only analyzes obligation (deontic) uses and you may argue that Alice's case is different, that is her ought is epistemic (logical necessity). I think it's both epistemic and deontic. Even when the deontic sense of ought isn't in focus, it's still at play because of its primacy (see The Cambridge Grammar of the English Language by Huddleston, p.186, Primacy of the deontic use)
Given all that, I think ought was used in the dialog not only for fun but also because it fits the context better. It's not interchangeable with should from the 19th century perspective. The only possible objection I can see is that the use of modals differed between AmE and BrE in that time.

Okay, I haven't read the article but I understand what you're saying now, more or less.

I think Alice's ought is epistemic, yes. That's exactly what I meant in my previous post.

Unfortunately, I don't have a copy of CGEL. Can you tell me what H&P say about the primacy of the deontic use?

As a footnote, I think it's also worth remembering that Carroll (Dodgson) was a professor of mathematics.