 Of course, the plausibility of this way of motivating the notion of nonconceptual content is a hostage to fortune in two important senses, one empirical and one philosophical. The argument rests upon an empirical claim about the appropriate way to explain the behavior of non-linguistic and pre-linguistic creatures—and in particular upon the assumption that it will not turn out to be possible to explain such behavior in non-psychological terms. But the argument also depends upon the thesis that the domain of behavior explicable in psychological terms extends further than the domain of concept possession—and this in turn depends upon a substantive philosophical account of what it is to possess a concept. If, for example, possessing the concept of an F simply requires being able to discriminate Fs from the rest of the perceptual environment and/or to act on them in a suitable manner, then it is hard to see how any evidence that animals and young infants represent the world will not also be evidence that they represent the world conceptually.