A NOTE ON STEVEN PINKER’S NOTE ON AN ASPECT OF “COMMON KNOWLEDGE”

 Steven Pinker:

“A lot of science fiction plots and comedies spell out what would happen in a world when people were completely honest. You might think, that would be great, no more hypocrisy and shilly-shallying and beating around the bush. But actually, as these comedies play out, this would be a nightmare. We don't want to live in a world in which everyone is completely honest. The reason is that our relationships depend on certain understandings that, when it comes down to it, are fictions. Like that two friends are completely loyal to each other and instantly generous. That couples are faithful, not just in action, but in thoughts. Now, we know that these are not quite reality, but still, we don't know that the other person knows that we know that they know. And that's what allows us to preserve the relationship. If everyone were to say what was on their mind at every time, who they fantasized having sex with, who they fantasized killing or harming, that would pollute the pool of assumptions that allows us to get along."

Me:

I’m trying to parse this part:

“We don't want to live in a world in which everyone is completely honest. The reason is that our relationships depend on certain understandings that, when it comes down to it, are fictions. Like that two friends are completely loyal to each other and instantly generous. That couples are faithful, not just in action, but in thoughts. Now, we know that these are not quite reality, but still, we don't know that the other person knows that we know that they know.”

Relationships, says Pinker,  depend on certain fictional understandings. His point hinges on “…we don't know that the other person knows that we know that they know.” 

My uncertainty goes to what happens to the argument if each knows that the other knows etc. etc. that each harbours less than ideal truths, that each maintains these fictions? 

And then, is his last point in this precise context about complete honesty as a relationship killer

“…If everyone were to say what was on their mind at every time…that would pollute the pool of assumptions that allows us to get along."

a non sequitur? 

Because if a person knew, say, that the other person fantasized about sexual partners, and each person knew that the other person knew that they knew and knew that they knew that they knew etc. etc., then what does that have to do with constantly uttering what’s on one’s mind?

And, given that each knows that the other harbours certain fictions and each knows that each knows that and each knows that each knows that each knows that etc. etc., then exactly what pool of assumptions are we talking about?