Saying that everybody knows is almost never a mistake. The statement isn’t sloppy reasoning. It’s a strategy that aims to cut off discussion or objection, to justify fraud and deception, and to establish truth without evidence.
This isn't my experience; I usually find people to use the expression "everyone X" out of frustration, in situations when they really do feel that everyone X, and can't believe that the other person thinks that not-X is normal or reasonable.
I think you missed an opportunity by only quoting the first verse of Cohen's Everybody Knows, because the second and third verses actually make a good chunk of the point you're trying to make, showing the ironic intent of the first verse as platitudes people use to be at peace with unpleasant things they can't personally change. The second verse presents this thesis:
Everybody knows that the boat is leaking
Everybody knows that the captain lied
Everybody got this broken feeling
Like their father or their dog just died
i.e., the need to avoid an unpleasant truth, as "Everybody talking to their pockets / Everybody wants a box of chocolates / And a long-stem rose... Everybody knows."
Then, the third verse shows the more argumentative and manipulative motte-and-bailey use of the phrase, as he accuses a lover of infidelity, despite the fact that "everybody knows that you love me, baby, everybody knows that you really do; and everybody knows that you've been faithful... ah, give or take a night or two".
i.e. the way people retreat to "but of course there are obvious exceptions... and everybody knows about those, too".
(The rest of the song, though, is kinda weird and I expect that it's stuff that's too culturally specific to the place and time where the song was written. Something something drugs, racism, AIDS, maybe nuclear apocalypse?)
One way to see this is to point out that when Alice tells Bob that everybody knows X, either Bob is asserting X because people act as if they don’t know X, or Bob does not know X. That’s why Alice is telling Bob in the first place.
It could also be that everybody (suitable quantification might be limited to: every student in this course/everyone at this party/every thinker on this site/every co-conspirator of our coup/etc) does in fact know X, but not everybody knows that everybody knows X. Depending on the circumstance of this being pointed out this can be part of creating common knowledge of X. This is related, but not identical to the fourth mode (of self-fulfilling prophecies) you describe. Consider the three statements:
X: "the king is wicked and his servants corrupt"
X': everybody in our conspiracy knows X
X'': it's common knowledge in our conspiracy that X
It's clear that saying X' can't make X true as long as our conspiracy doesn't leak information to the king or his servants. It's also clear that saying X' at a meeting of our whole conspiracy makes X'' true, and that this can be a useful tool for collective action. In fact if X' is not quite true (some people have doubts) saying it can make it true (if our co-conspirators are modal logicians using something like the T axiom).
From a more individualistic view-point such a statement of this form could still contain information if Bob does not know that he knows X (consider Zizek's description of ideology as unknown knowns).
What does the claim that ‘everybody knows’ mean?
I think you point to a valid type of problem with conspiracies of savvy and complicity, but mistakenly paint these as weapons asymmetrically favoring the forces of darkness. Perhaps the Common Knowledge framing makes it clearer, but the modes you describe are degenerate cases of tools for Justice:
The first central mode is ‘this is obviously true because social proof, so I don’t have to actually provide that social proof.’
The first mode attempts to look as deferral to experts on a question of fact. This often isn't as useful as discussing the object level, but might be more effective and legible if used as basis for a decision if the statement about expert opinion is not a lie.
The second central mode of ‘everyone knows’ is when it means ‘if you do not know this, or you question it, you are stupid, ignorant and blameworthy.’
We need to be able to punish defection in a legible way so it doesn't degenerate into blame games. For this we need common knowledge about these things so that people don't have excuses for saying or acting along the lines of not-X, but it really needs to be common knowledge so that people don't have excuses for not punishing defection on this point.
A third central mode is ‘if you do not know this (and, often, also claim everyone knows this), you do not count as part of everyone, and therefore are no one. If you wish to be someone, or to avoid becoming no one, know this.’
Restricting the universe over which you quantify can be really useful. In particular if you want to coordinate around a concrete project (like building Justice or a spaceship) it's necessary to restrict your notion of 'somebody' to a set that only includes people willing and able to accept certain facts/norms as given.
The fourth central mode is ‘we are establishing this as true, and ideally as unquestionable, so pass that information along as something everyone knows.’ It’s aspirational, a self-fulfilling prophecy. [...]
As mentioned above the self-fulfilling nature can be subtle, but it's not necessarily an ominous prophecy. It could be more along the lines of: "We all band together in accomplishing our goal, so we accomplish it and everyone who took part is greatly rewarded."
Similarly, this:
So they’ll cross their fingers rather than demand fair dice. So that they’ll stop trying to fight the war.
Is often not just false, but backwards.
The reason you say “everyone knows Bob is a liar” isn’t always to protect Bob and blame the victims for being fooled. Sometimes it’s to punish Bob, by taking things from the “trial” phase to the “sentencing” phase. So long as “Bob is a liar!” is a thing that needs to be said/argued, Bob is still on trial. Once “everyone knows” Bob is a liar, you can start actually treating him like a liar and trust that people will coordinate with you instead of against you for trying to punish someone whose guilt hasn’t been established.
Things often do get stuck at the stage where (pretty much) everyone knows but no one moves on to doing something about it because they feel they need to keep asserting the thing instead of declaring that it's worth taking as granted and moving on to dealing with it.
I agree that these are (sometimes) legitimate things to do, and that people often use the 'everybody knows' framing to do them implicitly. But I think that using this framing, rather than saying the thing more explicitly, is useful for those trying to do other things, and counter-productive for those trying to do the exact things you are describing, unless they also want to do other things.
Bob does not know X. That’s why Alice is telling Bob in the first place.
Conversational phrases aren't supposed to be interpreted literally. "Everybody knows" never means "literally every single person knows". This is about equivalent to complaining that people say "you're welcome" when the person really wouldn't be welcome under some circumstances.
Don't be the literal Internet guy who thinks this way.
Sometimes being overly literal is a useful way to point out hidden assumptions/inferences that the interlocutor attempted to sneak into the conversation (whether consciously or subconsciously).
Echoing the other replies so far, I can think of other practical explanations for saying "everybody knows..." that don't fall into your classification.
1) Everybody knows that presenting a fact X to someone who finds X obvious can sometimes give them the impression that you think they're stupid/uninformed/out-of-touch. For instance, the sentence you just read. For another instance, the first few slides of a scientific talk often present basic facts of the field, e.g. "Proteins comprise one or more chains of amino acids, of which there are 20 natural types." Everybody who's a professional biologist/biochemist/bioinformatician/etc. knows this [1]. If you present this information as being even a little bit novel, you look ridiculous. So a common thing to do is to preface such basic statements of fact with "As is well known / As everybody knows / As I'm sure you know / etc." [2]
No bad faith at all! Just a clarification that your statements are meant to help newcomers or outsiders who may not remember such facts as readily as people who work with them every day.
2) I find myself saying "but everybody knows..." to myself or the person I'm talking to when trying to understand puzzling behavior of others. For example, "everybody knows that if trash bags are left outside the dumpster, bears will come and tear everything up, so why do people keep leaving them there?" In this context, the "everybody knows" clause isn't meant as a literal truth but as a seemingly reasonable hypothesis in tension with concrete evidence to the contrary. If everybody has been told, repeatedly, that trash is to be put in the dumpster and not next to it, why do they act like they don't know this? Obviously there is no real mystery here: people do know, they just don't care enough to put in the effort.
But especially in more complex situations, it often helps to lay out a bunch of reasonable hypotheses and then think about why they might not hold. "Everybody knows ..." is a very common type of reasonable hypothesis and so discussion of this sort will often involve good faith uses of the phrase. Put another way: not all statements that look like facts are meant as facts and in particular, many statements are made expressly for the purpose of tearing them down as an exercise in reasoning (essentially, thinking out loud). But if you're not aware of this dynamic, and it's done too implicitly, it might seem like people are speaking in bad faith.
I guess what I'm trying to say in general is: "this statement of fact is too obviously false to be a mistake" has two possible implications: one, as you say, is that the statement was made in bad faith. The other, though, is that it's not a statement of fact. It's a statement intended to do something more so than to say something.
[1] Of course, even such basic facts aren't even strictly true. There are more than 20 natural amino acids if you include all known species, but, as everybody knows, everybody excludes selenocysteine and pyrrolysine in the canonical list.
[2] The alternative is to exclude these first few slides altogether, but this often makes for a too-abrupt start and the non-specialists are more likely to get lost partway through without those initial reminders of what's what.
For #1, the reason we do that is exactly because it is likely that not everyone in the room knows (even though they really should if they are in the room) and the people who don't know are going to be lost if you don't tell them. And certainly not everyone knows there are 20 amino acids (e.g. I didn't know that and will doubtless not remember it tomorrow).
I find your example in #2 to be on point: I am highly confident that far from everyone knows what happens if trash bags are left outside the dumpster. I actually had another mode in at one point to describe the form "I thought that everyone knew X, but it turned out I was wrong" because in my experience that's how this actually comes up.
For #1, I'm not sure I agree that not everyone in the room knows. I've seen introductions like this at conferences dedicated entirely to proteins where it assumed, rightly or not, that everyone knows the basics. It's more that not everyone will have the information cached as readily as the specialists. So I agree that sometimes it is more accurate to say "As I'm sure most of you know" but many times, you really are confident that everyone knows, just not necessarily at the tip of their tongue. It serves as a reminder, not actually new knowledge.
I suppose you could argue: since everyone is constantly forgetting little things here and there, even specialists forget some basics some of the time and so, at any given time, when a sufficiently large number of people is considered, it is very likely that at least one person cannot recall some basic fact X. Thus, any phrase like "everybody knows X" is almost certainly false in a big enough room.
With this definition of knowledge, I would agree with you that the phrase should be "as most of you know" or something similarly qualified. But I find this definition of knowledge sort of awkward and unintuitive. There is always some amount of prompting, some kind of cue, some latency required to access my knowledge. I think "remembers after 30 seconds of context" still counts as knowledge, for most practical purposes, especially for things outside my wheelhouse. Perhaps the most accurate phrase would be something like "As everyone has learned but not necessarily kept fresh in their minds..."
For #2, I should have clarified: this was an abbreviated reference to a situation in an apartment complex I lived in in which management regularly reminded everybody that bears would wreak havoc if trash were left out, and people regularly left trash out, to the delight of the bears. So I think in that scenario, everybody involved really did know, they just didn't care enough.
In addition to your cases that fail to be explained by the four modes, I submit that Leonard Cohen's song itself also fails to fit. Roughly speaking, one thread of meaning in these verses is that "(approximately) everybody knows the dice are loaded, but they don't raise a fuss because they know if they do, they'll be subjected to an even more unfavorable game." And likewise for the lost war. A second thread of meaning is that, as pjeby pointed out, people want to be at peace with unpleasant things they can't personally change. It's not about trapping the listener into agreeing with the propositions that everyone supposedly knows. Cohen's protagonist just takes it that the listener already agrees, and uses that to explain his own reaction to the betrayal he feels.
Besides being a really great object level post, I think it's also an great example of pointing to a subtle conversational move that appears pretty innocuous but upon investigation often is being used to sabotage information flows, intentionally or otherwise. I think a large part of rationality is being able to spot and navigate around these moves.
A version of this that I hear fairly often is “it’s common sense that...”
It works in the same way in that it makes it socially costly to argue against but is more insidious than “everybody knows” (at least in my circles “it’s common sense” has more of a veneer of respectability).
Both also have their proper uses which I think makes the improper uses more difficult to counter.
Another way to respond, rather than showing that it's not a correct statement, is to remember that it doesn't matter. "I don't care what people know, I care what's true".
This will be more effective on some topics than others, but that's true of any discourse tactic.
I... feel like this post is important. But I'm not actually sure how to use it and build around it.
I have vague memories of seeing this link-dropped by folk in the Benquo/Jessicata/Zack/Zvi crowd in various comments, but usually in a way that feels more like an injoke than a substantive point.
I just checked the three top-level-post pingbacks, and I do think they make meaningful reference to this post. Which I think is sufficient for "yes this concept got followed up on in the past 2 years". But I'm left with a vague frustration with the concept feeling slippery-er than it needs to be.
Maybe one problem is that this post is called "Everybody knows", and not "No, Everybody Doesn't No." So it's harder to namedrop it in a way that solidifies the concept rather than obfuscates it. (Similar to recent troubles with "Alike Minds Think Great", which ended up getting renamed to "Great Minds Might Not Think Alike")
I usually refer back to it by saying that someone is claiming everybody knows, and linking the words 'everybody knows.' I think it's the right title. And I find the ability to use the term everybody knows this way highly useful.
Once I got what this post was talking about, I really liked it. People linking to it made that abundantly clear (for me). But I didn’t get what the post was talking about first time I read it. I think the Cohen quote and the Dothraki saying didn’t help point me to the phenomenon the post is talking about. I might spend some time looking for an example that helps pinpoint it for me more quickly, if the post is highly voted, I think that would fix it for me.
“Everybody knows that the dice are loaded.
Everybody rolls with their fingers crossed.
Everybody knows the war is over.
Everybody knows the good guys lost.”
– Leonard Cohen, Everybody Knows
“It is known.” – Dothraki saying
It is not known. Everybody doesn’t know.
When someone claims that everyone knows something, either they are short-cutting and specifically mean ‘everyone in this well-defined small group where complex common knowledge of this particular thing is something we have invested in,’ they are very wrong about how the world works, or much more commonly, they are flat out lying.
Saying that everybody knows is almost never a mistake. The statement isn’t sloppy reasoning. It’s a strategy that aims to cut off discussion or objection, to justify fraud and deception, and to establish truth without evidence.
Not Everybody Knows
Let us first establish quickly that everyone doesn’t know. There are many ways to see this.
One way to see this is to point out that when Alice tells Bob that everybody knows X, either Bob is asserting X because people act as if they don’t know X, or Bob does not know X. That’s why Alice is telling Bob in the first place.
A second way is to attempt to explain something in detail as you would to a child.
A cleaner way is to consider some examples of things that a lot of people don’t know. According to the first Google hit, 32 million American adults can’t read, and 50% can’t read a book at the 8th grade level. Various other tests of basic skills from school don’t look much better. Here are some more basic facts many Americans don’t know, including 20% who think the Sun revolves around the Earth. Nigerian prince scams still make over $700,000 per year. Doctors can’t do basic job-relevant probability calculations within an order of magnitude. Just yesterday (as of writing this) I had to explain to a college graduate that Bitcoin was more volatile than the stock market, and Forex was not a responsible retirement savings plan.
What does the claim that ‘everybody knows’ mean?
There are a few different things ‘everybody knows’ is standing in for when someone claims it.
In most of them, the claim that literal actual ‘everybody knows’ is sort of the Bailey, and the thing we’ll describe here is the implicit Motte that ‘everyone knows’ is your real message. Which of course, in turn, not everybody knows. As is often the case, the Bailey is blatantly false. But demonstrating that is socially costly. It shows you are the one who does not get it, who is not in on the goings on. So much so that when someone ‘calls someone out’ on a blatant lie, the liar socially benefits.
I see four related central modes. They overlap and reinforce each other, and are often all in play at once.
The first central mode is ‘this is obviously true because social proof, so I don’t have to actually provide that social proof.’
Often the proof in question doesn’t exist at all. Other times, it’s a plurality of ‘experts’ in a survey, or a reporter’s reading of a single scientific study, or three friends backing each other up – or people who have been told or gotten the impression everybody knows, so they claim to know, too. The phrase ‘everybody knows’ is a great way to cause an information cascade.
The second central mode of ‘everyone knows’ is when it means ‘if you do not know this, or you question it, you are stupid, ignorant and blameworthy.’
It’s your own damn fault for going out in the rain and getting soaked. It’s your own damn fault for not knowing that everything politicians say (or something the speaker said) is a lie, even though they frequently tell the truth – which means they ‘aren’t really lies’ because no one was fooled. It’s your own damn fault for not keeping up with the latest gossip or fashion trends.
It is made clear that to question this is to show you are stupid, ignorant and blameworthy, especially if the statement everyone knows is false. You’d be all but volunteering to be the scapegoat.
A classic mode is the condemnation ‘everyone knows that X is (everywhere / great / the right thing / necessary / patriotic / fair / standard / appropriate / customary / the party line / how things get done around here / smart / right / a thing / not a thing / a conspiracy theory / wrong / evil / stupid / slander / rhetoric used by the out-group / rhetoric that supports the out-group / unacceptable / impossible / impractical / unthinkable / horrible / unfair / stupid / rude / your own fault / racist / sexist / treason / cheating / cultural appropriation / etc etc etc).
The whole point is to establish truth without allowing a response or providing evidence.
Note that this is self-referencing. To be someone, you have to know what ‘everybody knows’ means.
A third central mode is ‘if you do not know this (and, often, also claim everyone knows this), you do not count as part of everyone, and therefore are no one. If you wish to be someone, or to avoid becoming no one, know this.’
This works both to make those on the outs not people, and to make the statements used unquestionable.
Thus, one is not blameworthy for acting as if everyone knows, because if someone is revealed not to know, that means they are no one, and therefore they have no relevant impact or moral personhood. They can be ignored. Perhaps those who do not know this, or question it, are the outgroup. Perhaps they are simply those who don’t get ahead, the little people. Perhaps they’re just the fools we pity. Regardless, until they catch on, it is good and right to scam them – it is a sin to let a sucker keep his money.
A key variation on this is to flip the order into a way to admonish someone when they expose a falsehood or fraud someone wishes to perpetuate. First they argue that the thing is not a fraud, ideally that everyone knows it is not a fraud, but they lose, they fall back by flipping their position entirely. They now say: You’re calling this thing a fraud. But everyone knows it’s a fraud, so why are you wasting everyone’s time saying it’s a fraud when everyone already knows? This must be a social tactic, trying to lower the status of the fraud by pointing out what everyone already knows. Or if you think we don’t already know, that must mean you think we aren’t anyone. How insulting.
The fourth central mode is ‘we are establishing this as true, and ideally as unquestionable, so pass that information along as something everyone knows.’ It’s aspirational, a self-fulfilling prophecy. Perhaps we already have done so by the time you’re hearing this (and that’s bad, because it means you’re not hearing about new things everyone knows quickly enough!) or perhaps you’re the first person to be told.
Either way, join the conspiracy. Spread that everybody knows the dice are loaded and rolls with their fingers crossed. Spread that everybody knows the war is over, and everybody knows the good guys lost.
So they’ll cross their fingers rather than demand fair dice. So that they’ll stop trying to fight the war.