Do you believe in Efficient Market Theory (EMT)?

You're familiar with the old joke about the economist who won't pick a twenty-dollar bill off the sidewalk, because if it were really there someone would have picked it up already. All right. So Efficient Sidewalk Theory (EST) says that there are no twenty-dollar bills on the sidewalk, because they've been picked up.

Efficient Sidewalk Theory shares the defect of Efficient Market Theory that if everyone believed it absolutely, like the economist in the joke, then no one would pick up twenty-dollar bills and they would accumulate on the ground.

But, although an absolute belief in Efficient Sidewalk Theory leads to absurdity, nevertheless I would say Efficient Sidewalk Theory is substantially true. Almost no sidewalks have twenty-dollar bills on them, because of the tendency for passers-by to pick up the bills.

Practical consequences: Although I'll pick up a twenty-dollar bill if I see one, I'm not inclined to go on long walks in order to look for one. And if someone wrote a book about their "system" for finding dropped bills (check near ATMs and outside stores; go looking in January when people have cold fingers and wear gloves), I would be inclined to think that, while their system might have some merit, it probably does not have a lot of merit, because of Efficient Sidewalk Theory.