 Popper has emphasized that we are theorizing all the time. Consider the observation of a glass full of clear liquid. Suppose it’s water. Then it quenches thirst and extinguishes fires and nourishes plants. But what if it’s alcohol instead? Just describing it as “water” entails innumerable subjunctives about the kinds of responses it would display under a wide variety of test conditions. They are the would be’s of things of that kind. Consider the differences between basket balls, billiard balls, and tennis balls. Things of different kinds can do different things. Even the seemingly simplest observation of a rabbit in the backyard, for example, implies that it is going to display rabbit-like behavior, including eating carrots when my wife puts them out. It is going to hop around and create more rabbits. If it’s a rabbit, it is going to have rabbit DNA. It will not turn out to be stuffed. And this suggested that observational properties and predicates are dispositional, too.