It’s altogether fitting that Philmon now co-blogs at Rotten Chestnuts, since these two concepts are really sides of the same die – they both refer to falsehoods that somehow have become things that “everybody knows.”
By itself the concept is useful; you could argue that it is even indispensible. There is simply no possible way that any meaningful exchange of ideas could go on if there was no large shared body of basic facts and concepts that were known to all parties beforehand. We’ve all had the experience of talking at cross-purposes for what seems like an hour, astounded that what we’re saying makes no sense at all to the other fellow, only to be brought full-stop when we realize that a crucial bit of background is entirely missing, without which the other person has literally no idea what we could be talking about. “My uncle died last week.” OOOOOOHHHHHHH….
Imagine having to stop to revisit the meanings of every possible idea, fact, and theory influencing what you were discussing, and then think of how long a job that would be when you realize that those things all themselves rest on other information that then has to be revisited and discussed, and then think about how long that would all take if your partner then asked for documented evidence for it all? We wouldn’t be able to ask for a cup of coffee without explaining that coffee typically comes in beans that have been roasted, so these beans should first be ground, which means taking the whole beans and fragmenting them to a coarse powder, and that this powder should be placed in a porous filter so that water can pass through it but the powder remains, and that the water should be heated to near-boiling, and that boiling means turning liquid into gas, and since we need liquid water it shouldn’t boil but it should still be hot, and that then the hot liquid water should be poured through the grounds in the filter and the resulting beverage should be collected in an empty vessel, and that once the vessel is full of this beverage it should be passed to us that we might drink it, and in exchange we will give you one dollar and fifty cents, because we use money as a convenient medium of exchange for our labor vis-a-vis goods and services, and one dollar and fifty cents of my labor is the equivalent of this beverage plus your time in making it and the cup you hand it to me in and etc. etc… and do you have any cream?
The problem comes when what everybody knows is, in fact, false.