 The conclusion of this first stage is, therefore, that a causal theory of mental representation requires a LOT. In the other stage of his argument, Cummins observes that, for a wide range of objects, their perception is mediated by a body of theory. Thus, to perceive dogs—for dogs to cause “dogs”—one has to know things such as that dogs have tails, dogs have fur, and dogs four legs. But, to know that dogs have tails, fur, and four legs, one needs a set of mental representations, such as “tail”, “fur”, “four”, and “legs”. Now the problem fully emerges. According to causal theories, having an “X” representation requires the ability to detect dogs. But, the ability to detect dogs requires a theory of dogs. But, having a theory of dogs requires already having a LOT—a system of mental representation. One cannot generate mental representations without already having  them.[12]