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.
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.