Mastodawn

Denny Vrandečić May 20

"Maria and Peter are students and meet up for a late dinner. Peter asks Maria whether Tom is at the party that they intend to go to after dinner. Maria answers that Tom is at the party. After all, Tom had told her that he would be at the party. When they arrive at the party, it turns out that Tom had changed his plans, and is not at the party. Was Maria's answer true or false?"

#truth #philosophy #cognition

(please spread for visibility, I would like this to be as wide as possible)

1/2

Maria's answer was true

32.6%

Maria's answer was false

67.4%

Poll ended at 3:52pm.

Denny Vrandečić May 20

A new study shows that there is much, much less agreement on the answer to this question than I would have expected. Even after reading about the study, I still expect people in my bubble to have the same answer as I do. Let's see. But this probably means that the meaning of truth, in the general population, is simply different from what I would have assumed. And explains a number of public discourses.

2/2

https://reason.com/2026/05/15/the-surprising-divide-over-what-counts-as-true/

New study investigates why people disagree about what's true

A new study finds that what people think about facts, authenticity, or coherent beliefs explains why they disagree about what is true.

Reason.com

@vrandecic so some people equate someone lying to someone's statement being false? Then they should have a different word for someone being unintentionally wrong?

Denny Vrandečić May 20

@janjko yeah, I have the same problem. I would say Maria never lied. But for me, that doesn't mean what she said is true.

Rob van Kan🔻May 20

@vrandecic @janjko as far as she knew, it was true.

@edgeofeurope @vrandecic @janjko No, she had no way of knowing it was true.

@bnlandor @edgeofeurope @vrandecic @janjko We can never be absolutely certain of anything at the level of logic.

This seems mainly to be a problem about the practice assigning logical truth values to real life language acts.

It seems we can all agree on the practical meaning, consequences, and so on, and whether the different parts of the bundle of things we might mean by a statement being true are satisfied and what they might be contingent on (the personalities of the people, their circumstance, etc)..

Where we disagree seems to be on this truth-value labelling pursuit which, a bit like village cricket, I'm pleased some people are passionate about, but I'm not sure I'm one of them.

bor[x]a 🇵🇸 ボルシャ

@chiffchaff well, modality exists @bnlandor @edgeofeurope @vrandecic @janjko

@protoeuskaldun @bnlandor @edgeofeurope @vrandecic @janjko Dunnocks much more so.

bor[x]a 🇵🇸 ボルシャ

@chiffchaff LOL, sorry for my brief reply; what I meant was that the question posed at the start has a clear logical answer for me, as Maria could have used some form of modal or evidential marker. By not doing so, even if she wasn’t lying intentionally, her statement lends itself to a fairly straightforward assessment of falsity. @bnlandor @edgeofeurope @vrandecic @janjko

@protoeuskaldun @bnlandor @edgeofeurope @vrandecic @janjko sorry, I thought you were making a claim for the foundational importance of truth values of utterances in building a model of the world.

Maria could have been clearer about her level of knowledge, to make the surface meaning match the pragmatic purpose, but that can be a tedious fool's errand if you go too far with it in real life.

Daniel Gibson 1d ago

@chiffchaff @protoeuskaldun @bnlandor @edgeofeurope @vrandecic @janjko
At what point could she be 100% sure anyway? Even if he had told her earlier that he was at the party he could've left by then...
If she knew him to be chained to the wall at that party? Even then he might have died by now, which opens another can of worms about the definition of *being* at the party :-p

It's obvious that she could only answer with what she knew at the time and that a "yes" implies "as far as I know"

@Doomed_Daniel @protoeuskaldun @bnlandor @edgeofeurope @vrandecic @janjko it could be an alien hologram of him, or she could be afflicted by psychosis, or whatever. I think it's okay to say false things by accident when the world is conspiring against you, but here, as long as the questioner had a fair understanding of the answerers level of knowledge, I think "is" is just a placeholder for a complex construction already understood by context by both parties. If I ask "Is there a film at 11?" at 9, I think I can say yes truthfully, without saying "as long as there isn't a major international incident in the next two hours. That "is" is clearly about scheduling.

Evelyn Estelle 54m ago

@chiffchaff @Doomed_Daniel @protoeuskaldun @bnlandor @edgeofeurope @vrandecic @janjko

Or you can just cut out all the uncertainty and assumption and say "he said he will be at the party" or "yes, the film is scheduled at 11".

Hiker Geek 🌲💻🌲4d ago

@bnlandor @edgeofeurope @vrandecic @janjko

I think she can be pretty sure that it's true Tom told her he would be at the party.

What Tom said to her wasn't true.

Melvin Gundlach 4d ago

@HikerGeek @bnlandor @edgeofeurope @vrandecic @janjko Yes, but that wasn’t the question. If the question was if Tom *said* he would be at the party, then yes. As it is written, Maria’s statement is false (even though not an intentional lie).

tessarakt 4d ago

@bnlandor @edgeofeurope @vrandecic @janjko Which Peter knew. So his question must be understood as being about her belief according to the information available to her.

Siderea, Sibylla Bostoniensis 1d ago

No, that logically does not follow. By normal convention all requests for information are accompanied by the implicit qualifier, "if you know".

This is precisely why LLMs never answering "I don't know" and instead hallucinating an answer is such a violation of the social compact.

@bnlandor @edgeofeurope @vrandecic @janjko

@siderea @tessarakt @edgeofeurope @vrandecic @janjko Does that affect the truth value of her statement in any way? Not any potentially implied statement, but the actual statement.

Siderea, Sibylla Bostoniensis 1d ago

@bnlandor
Of course. Allow me to demonstrate.

Imagine that you say to Maria, "Oh, hey, I see there's a party at Jane's place. Is Tom at the party?" and Maria, knowing perfectly well that Tom is not at Jane's party but Susie's party across town, and not wanting you to know that, deliberately trades on ambiguity to deceive by saying, "Yes, Tom is at the party." Further imagine that you subsequently find out that Tom was not at Jane's party but at Susie's party, and Maria knew that, and you confront Maria, "Hey! Why did you tell me that Tom was at Jane's party when you knew he was at Susie's party?"

Imagine that Maria replies, "I did no such thing. I didn't tell you that Tom was at Jane's party. I said he was at *the* party."

This would be pretty universally agreed to be a specious argument.

This is because the truth or falsity of an answer to a question is only determinable in the context of the question it is answering.

So it turns out to matter pretty enormously to the truth or falsity of Maria's answer to Peter just which question she was answering when she uttered it.

@tessarakt @edgeofeurope @vrandecic @janjko

tessarakt 1d ago

@siderea @bnlandor @edgeofeurope @vrandecic @janjko "This would be pretty universally agreed to be a specious argument."

However, the US Supreme Court might consider it literally true under the Bronston literal truth defense. https://en.wikipedia.org/wiki/Bronston_v._United_States

Bronston v. United States - Wikipedia

@siderea @tessarakt @bnlandor @edgeofeurope @vrandecic @janjko I don't see the comparison to an LLM. LLMs are expected to say "I don't know" and fail to when they produce answers they have no basis for in either direction. Maria did have (very strong) basis for her answer, even though it happened to be wrong.

Siderea, Sibylla Bostoniensis 1d ago

@orman Depends on what you mean by "expected". A lot of people expect LLMs to say "I don't know" and notoriously LLMs rarely if ever say "I don't know" and this is this a violation of that expectation if you have it.

@tessarakt @bnlandor @edgeofeurope @vrandecic @janjko

Jeff Grigg 1d ago

@siderea @orman @tessarakt @bnlandor @edgeofeurope @vrandecic @janjko

Expecting LLMs to say "I don't know." is an unreasonable expectation. That's not what they're built to do. And LLMs don't actually "know" anything, in any strict logical "thinking" sense. They're designed to produce plausible sequences of text. The truth or falsity of their statements is irrelevant. If fed text of many humans lying, as training input, the LLM will do the same, without regret or even "thought."

Sarah Peper 🏳️‍⚧️🇺🇦1d ago

@bnlandor @edgeofeurope @vrandecic @janjko but this is the default. I automatically parse her statement as "I believe he will be there", because the actual fact is unknowable at that point. We just use shortcuts to not use "to the best of my knowledge" in every sentence we say