This chapter continues the themes from Chapter 4 as well as my episode all about probability, risk and Bayesianism found here: https://www.youtube.com/watch?v=AOK5aiASmKM which is an exploration of another talk given by David Deutsch on the nature of probability given what we know about physics. So this chapter of Pinker's book Rationality - being centrally concerned about the use of what is called "Bayesian Reasoning" is compared in this episode to alternative explanations of what rationality and reason amount to. More than previous episodes so far that I have published on the book "Rationality" this one is very much a critique. There is much to recommend the book "Rationality" for two reasons (1) it does summarise and explain some common misconceptions about how to reason or common mistakes people make when reasoning - and these are worth knowing (2) it works as an excellent summary of the prevailing intellectual/academic perspective on these matters for people who are interested in what the truth of the matter is. Knowing what "academic experts" think about this stuff means knowing what gets taught and what filters eventually into culture itself via the "top down" education system we presently have. All that is worth knowing. But here, in this chapter, we encounter the fundamental clash of epistemological worldviews: the mainstream intellectual *prescription* of what they think should be the way people think as against Karl Popper's *description* of the reality as to how knowledge is generated and progress made through incremental identification of errors and their correction. Have fun listening!