The point is promote common knowledge https://en.wikipedia.org/wiki/Common_knowledge_(logic) https://en.wikipedia.org/wiki/Common_knowledge_(logic) It's a term

The point is promote common knowledge https://en.wikipedia.org/wiki/Common_knowledge_(logic) https://en.wikipedia.org/wiki/Common_knowledge_(logic) It's a term of art, describing a kind of knowledge. You might think something is common knowledge if everyone knows the thing, but that's not the technical meaning. In the technical meaning, they also have to know that each other knows it and know that the other ones know that each one knows it, and so on. You might think there's no difference, but if you think about it you can imagine some situations where you make different conclusions from 'everyone knows the thing' vs. 'the thing is common knowledge'.