Re: I sum up Burton's conclusion differently.
Yes, I think he did say that this useful, necessary feeling of certainty is also our greatest obstacle to mental flexibility. Of course, he didn't use the term absolute truth, which is a slippery term, but my guess is that he would want to wave a caution flag at such words, as well he should, I believe. His approach is brain-centered. My brain may be aflame with certainty about truth, which is fine I suppose, but what gets me into problems is when I proclaim that certainty to have a universal application, for everyone. That's what tags the "absolute" onto truth.