I think the problem may be what counts as correlated. If I toss two coins and both get heads, that's probably coincidence. If I toss two coins N times and get HH TT HH HH HH TT HH HH HH HH TT HH HH HH HH HH TT HH TT TT HH then there's probably a common cause of some sort.
But real life is littered with things that look sort of correlated, like price of X and price of Y both (a) go up over time and (b) shoot up temporarily when the roads are closed, but are not otherwise correlated, and it's not clear when this should apply (even though I agree it's a good principle).
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.)