The Limits of a Longitudinal Study

There's 100 million Ravens in the world, but there are untold quadrillions of non-black things in the world. So however many you look at, you're not really going to learn anything about Ravens. People often use the logically equivalent formulation in order to confirm something where they can so they can confirm it much more easily than if they actually went out and studied the thing. The lazy person's way of casting the Raven hypothesis is silly because I don't know where there are.