Going through Jeff Gill’s Bayesian text book

when I came across the line:

From the Bayesian perspective, there are two types of quantities: known and unknown. (43)

This seems to be from the pre-9/11 school of thought as Rumsfeld* has us living in a more complicated world:

I guess technically I should exclude unknown knowns – that is, those things we did not know that we already knew.  I also have written the words “know” and “known” far too many times that it no longer appears to be a real word anymore.

*“Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns — the ones we don’t know we don’t know.” ~ Donald Rumsfeld, quote recently appropriated from one of Aparna Kher’s dissertation chapters.

Michael A. Allen, Bayesian Statistics engages in Pre-9/11 Thinking….

, published September 23, 2008 at The Quantitative Peace.