The idea is (p. 218): feelings of knowing/correctness/certainty aren't deliberate conclusions and conscious choices but mental sensations that happen.
The topic of how we know and what we believe is very worth consideration. That said, while the idea is intriguing, the author doesn't do a great job of providing more than his ruminations of his thoughts developed over the course of his career. That is this is a layperson's book written with no citations of research, data, etc. Overall, somewhat disconcerning.