Imagine you have two cabinets in your kitchen. One is labeled “Poisons,” and the other is marked “Tasty Treats.” Okay, it’s a strange kitchen. On the counter below are two identical containers. They are identical in every way—same weight, same size and same appearance. Neither container is labeled. One of the containers is near the cabinet that says Poisons, the other is near the cabinet that says Tasty Treats. It might be a fair guess that the one near the Treats cabinet is just that—something good to eat. The other one must be for rattraps.