One of the foundations of Chomsky’s theory is that language is a mode of thinking, an internal system, rather than a communicative one. In part 2 of this book I document the internal structures on which language depends, but I argue that these are not specific to language, nor did they emerge suddenly in our own species. Rather, they are the outcome of normal evolutionary processes of mental adaptation to a spatial world with growing social imperatives. In this view language is shaped to allow us to share internal thoughts, and indeed may be uniquely equipped to do so in our species. In order to understand how it does this, we must consider the nature of thought itself. Indeed, as we shall see, some of the attributes of language are indeed dependent on the nature of our thoughts and experiences, although not in the manner proposed by Chomsky.
Chapter 4 argues for a clear distinction between language and thought, and it develops the argument that one aspect of thought that shaped language as a communication system is the ability to travel mentally in time and place. This leads to the feature of language known as displacement, allowing us to refer to events that are nonpresent. We can describe events that occurred in the past or that are planned for the future, or even events that are purely imaginary. I will suggest that the capacity to travel mentally in time is not unique to humans but evolved incrementally throughout the evolution of animals that inhabit and move around in spatial environments. What does seem to be distinctive to humans is not mental time travel itself but the capacity to share our travels.
In chapter 5 I discuss another kind of mental travel, our excursions into the minds of others. This is known as theory of mind and is also critical to language. Indeed, effective communication is at best crippled if speaker and audience do not share a stream of thought that is only partially determined by language. Theory of mind may well be more highly developed in humans than in other living species, although there are at least some indications that primates, and especially the great apes, have limited access to what others are thinking or feeling.
Chapter 6 brings mental time travel and theory of mind together into perhaps the most distinctive of human activities, the telling of stories. Of course stories themselves are generally told through language, although in the modern age movies, videos, and TV soaps—not to mention comic strips—can add a substantial nonlinguistic element. The basis of stories is the mental journeys we are able to take into other places, other times, and other minds, often into realms that are pure fantasy. Although language is critical to the telling of stories, it is distinct from the stories themselves.