This chart from a Wall Street Journal editorial has been making the rounds lately, being ridiculed left and right. A number of you have been leaving comments here so I'm putting it up and center as our light entertainment for the week.
The chart is being used to justify this economic concept called the "Laffer Curve" which claims that lowering tax rates can increase total tax receipts (for example, because fewer people will cheat the government.) As far as I know, it is dogma, and has never been proven empirically.
I also agree with Prof. Gelman's skepticism about using countries as experimental units to inform domestic policy.