 The need for supplementary information is too pervasive and too important to be a matter of something specifically linguistic, as might be suggested by Grice’s conversational principle and maxims. Sperber and Wilson see the fundamental mechanism of such inferences as going well beyond language, and beyond humans. In terms of Carston’s distinctions, relevance theory departs from Grice’s philosophical project, and aims at an empirical psychological theory of human cognition and communication. They see the phenomenon they call ‘relevance’ as a psychological phenomenon basic to the lives not only of humans but of all animals with a cognitive repertoire sophisticated enough to have choices about which environmental cues to attend to. Evolution shapes the phenomenon of relevance; an animal’s attention is drawn to environmental cues that provide the most crucial information. Sounds of an approaching cat grabs a bird’s attention away from a worm; parents are alert to the sounds of their baby’s crying. The phenomenon is extended through learning; the squeal of brakes grabs a driver’s attention away from a pretty sunset. And the cues can be conventional; the dinner bell grabs the attention of the hungry child. The phenomenon of relevance in language is another manifestation of this very general phenomenon. ‘Relevance’ in relevance theory, then, should not be taken to be just our ordinary conception of relevance; nor should it be equated with the ‘relevance’ of Grice’s maxim, although it is connected to that and intended to provide a deepened understanding of what underlies the maxim.