I've written before about how we need Cross Silo Flow Metric Visibility in relation to patient flow data. Each silo (by which I mean each specialty, or each clinical directorate) has to be able to see not only their own flow metrics, but every other silo's flow metrics, too.
But here's a new slant on this idea. I've been watching videos of Steven Pinker talking about his new book (When Everyone Knows That Everyone Knows...) that's due to be published later this month. He talks about this idea that—in a lot of situations—it's not enough for me to know something and for you to know that same thing. In addition, I've got to know that you know that I know that thing. And you've got to know that I know that you know that thing. And so on.
When all of that happens, that's when we get what Steven Pinker (and everyone else, for that matter!) calls common knowledge. And it occurred to me as I watched these videos that we need to apply this idea to patient flow metrics and this notion of cross-silo flow metric visibility.
For example, it's not enough for the clinical director of the Emergency Department (ED) to know what's going on in the Acute Medical Unit (AMU) as well as the Emergency Department. And it's not enough for the clinical director of Acute Medicine to know what's going on in the ED as well as in the AMU.
If that's all that's happening, we've just got shared knowledge. Better than private knowledge, yes. But not as good as common knowledge. For this to become common knowledge, the Acute Medicine clinical director has got to know that the ED clinical director knows that she knows. And the ED clinical director has got to know that the Acute Medicine clinical director knows that he knows that she knows. And so on.
It's only common knowledge that enables the possibility of mutual obligation. Or joint responsibility. Or shared endeavour. Or whatever name we want to give to this challenge of improving patient flow in hospitals.
But here's the scary bit. Pinker talks about there being—in this context—three types of knowledge.
First of all, there's private knowledge (the ED clinical director knows what's going on in the ED and in AMU - and everywhere else).
Secondly, there is shared knowledge (the ED clinical director knows what's going on in the ED and in AMU and everywhere else and so does the Acute Medicine clinical director also know what's going on in the ED and in AMU and everywhere else).
Thirdly, there is common knowledge (Each knows that the other knows, and each knows that the other knows that the other knows etc. etc.) And it's only when we get to common knowledge that we can work effectively as a team.
But when it comes to patient flow, in most hospitals we're nowhere near the common knowledge stage. Nor even the shared knowledge stage. In fact, we haven't yet reached the private knowledge stage: we’re still stuck at zero knowledge.
[8 September 2025]
[This originally appeared as a thread on X.]