Pär Segerdahl, Language Use, Ch.3, "Context Dependence"

The meaning of a sentence is not determined by the meanings of its component words, it is determined by how it is used. Systemaic variations in the meanings of sentences should be explained in terms of variation in use, not in variation in their component parts. It is wrong to think that there are isolable linguistic items like words and sentences; a demonstrative like "this book", for example, includes the book as part of the symbol. The question of what must be added to a linguistic item, like "this book", to deliver a unique reference is confused. It is confused because it treats language as separated from the world.