Their tendency to rely heavily on appeals to authority, e.g., "the science is settled".
...when countering the equally generic claim that the science is not settled.
Specific criticisms receive specific replies; generic criticisms receive generic replies -- not because more specific replies aren't available, but for the tactical reason that a generic criticism is trivial to generate whereas a specific reply to a generic criticism is exhausting to generate.
People want to tell everything instead of telling the best 15 words. They want to learn everything instead of the best 15 words. In this thread, instead post the best 15-words from a book you've read recently (or anything else). It has to stand on its own. It's not a summary, the whole value needs to be contained in those words.
I'll start in the comments below.
(Voted by the Schelling study group as the best exercise of the meeting.)