Short excerpt from a YouTube conversation (Dr. Arthur Brooks) exploring whether non-human species can have 'common knowledge.' SPEAKER A argues that other species use conspicuous public signals (e.g., full moon timing for coral spawning; eye contact, laughing, crying, blushing in animals) as coordination shortcuts that function like common knowledge without higher-order reasoning.
Given the fact that common knowledge is unbelievably nuanced and complex, are Homo sapiens the only species that are equipped to have common knowledge? Or is there common knowledge between dogs and pigeons and other species?
So here's the thing about common knowledge. Your head starts to explode when you think too many layers of I know that he knows that I know that he knows. I think we do see in other animals. That's why eye contact is such a potent signal in many species, it can be usually as a threat. And they're also species that manage to coordinate with some public common signal, even though they're certainly not thinking anything. So I give the example of coral, which don't even have a brain to think with, but they all release their eggs and sperm into the water on the full moon. The full moon is the equivalent of them all knowing that each of the other knows. They all have to pick one day. Doesn't matter what day it is, as long as it's the same day. And the full moon being a conspicuous public signal is all they need to do it. And so that's a shortcut that brainless coral use. It's the shortcut that we use when either something is out there and you can't ignore it, like it's being blurted out, or we make eye contact. We have other signals that make it clear that not only do we know something, but we know that the other person knows it. Like eye contact, like laughing, like crying, like blushing, that generate this common knowledge.
