Most political observers — or, any observer, really — found Clint Eastwood’s speech Thursday night really, really weird. Rachel Maddow was rendered speechless before describing it as “the weirdest thing I’ve ever seen at a political convention in my entire life, and it will be the weirdest thing I’ve ever seen if I live to be 100.”

It was weird, but it certainly was not unprecedented. Smithsonian Magazine does some digging and finds that there’s actually a decent amount of empty-chair debates in American political history. It stretches back to at least 1924, when progressive party vice-presidential nominee Burton K. Wheeler “took a stab at an invisible President Calvin Coolidge.”...