In the case of hermit crabs, we find the relevant behavioral pattern. So, we may infer that, like us, they feel pain. To be sure, they have many fewer neurons. But why should we think that makes a difference to the presence of pain? It didn’t make any difference with respect to the complex pattern of behavior the crabs display in response to noxious stimuli. Why should it make any difference with respect to the cause of that behavior? It might, of course. There is no question of proof here. But that isn’t enough to overturn the inference.