Linguistics is a relatively young science, and psycholinguistics and computational linguistics are even younger, so it's not surprising that these fields are still fraught with controversy. Though there is general agreement on some core topics, some quite basic issues are still up in the air. It is not the place of an introductory textbook to go into all of the controversies; I will only try to do this for one topic, language learning, perhaps the most hotly debated of all. But it is impossible to discuss any topic related to language without taking some sort of stand on the questions that divide language scientists. All linguistics textbooks take such a stand, though, sadly, few of them tell you that they are doing this. The stand taken in this book is that language and language behavior are not phenomena separate from the rest of human perceiving, acting, and reasoning; that we can only understand how language works by understanding how it fits into the rest of human behavior. Another way to think of this position is that we will be treating the language sciences as cognitive sciences.
This position is related to two of the ways of looking at and studying language that we've already discussed. As noted in the overview of the book, we can study language as a system independent of the people who use it, or we can study language behavior, focusing on use. As noted in the section on how language is studied, we can be concerned with product or process. The stand that this book takes implies that it cannot be enough to study language as a system in its own right (though it might be useful some of the time to do this) or to study product rather than process (though again it may be useful some of the time). It also implies that the border between language and non-language is not necessarily a clear one and not something we should spend much time worrying about. So for every topic covered in this book, I will try to look at it both ways, to see how the system/product perspective and behavior/process perspective both contribute to an understanding of how language works.
I didn't invent this position of course. A number of other people have defended one or another aspect of it. On the need to consider cognitive processes outside of language in order to understand language, cognitive linguists like Ronald Langacker and George Lakoff have made this case in many of their writings, in which they invoke general psychological notions such as attention, categorization, and memory. On the need to treat language as process, a very convincing argument was made in 1983 by the computer scientist Terry Winograd in his important book Language as a Cognitive Process (1983).
In the rest of this section, I discuss two themes that are consistent with this stand and that will guide the rest of the book.
Meaning, Function, and Form
The Main Theme of the book is that language associates meaningand function with form and that understanding how language works requires that we focus on these associations. All three of these terms will become clearer later in this book. For now we will just try to get the gist of what's intended by them.
Linguistic form concerns the way a linguistic expression sounds (for spoken language) or looks (for written or signed language) or how a linguistic expression is produced. There are two ways of looking at form. The usual way within linguistics is to think of form as a sequence of elements. For written language this is a natural way to treat form because written sentences are sequences of elements (characters). For spoken or signed language, it is less so. Treating a stretch of spoken or signed language as a sequence of elements means in effect focusing on the written transcription of the language in terms of units of sound or primitive gestures of some sort. This approach tends to play down the role of time, to look at a stretch of language as a static object. An alternative and more radical way of looking at form (at least for spoken or signed language) is to treat a stretch of language as something inherently continuous and dynamic, something that cannot (or should not) be transcribed as a written sequence of elements. In this book, I will usually discuss linguistic form in the first way, mostly because this is the way it is usually done and because it seems to simplify the analysis. But I will also insert periodic warnings about the biases that are built into this approach. One particular bias we should be aware of is one based on literacy; that is, as skilled users of alphabets, we may tend to think of spoken and signed language in this way (for an argument of this sort, see this paper by linguist Robert F. Port).
I will use meaning to refer to what language is about, the concepts that words and linguistic patterns refer to. By concept I will mean a unit of cognitive experience, a way people have of abstracting over their experiences in the world. For example, in a baby's experience the same face keeps appearing over it, and the baby abstracts over these different occurrences of face-appearing the concept of daddy. In this book labels for concepts will often appear like this. If the nature of form in the study of language is controversial, the nature of meaning is even more so. Some people deny that there is such a thing as meaning or that talking about meaning is helpful or that there is a consistent way to define "meaning" or "concept" or "about." I will try to take these positions seriously in this book, but the fact is that I don't know how to even get started without looking at the pole of language that is opposed to form.
Concepts without Words
Whatever we mean by concepts, it is clear that not all of them are associated with words. Words are linguistic; concepts need not be. We all have concepts that we have no words or grammatical patterns for. For example, one concept I have is the little depressed region bounded by two vertical ridges that is found between the nose and the middle of the upper lip. I have no idea what to call that place (though I'm pretty sure it has a name in at least some languages); that concept does not represent the meaning of a word for me.
Another point to note here is that meanings do not need to be seen as thing that are "out there" in the world. Since the stand taken in this book is that language is basically a cognitive phenomenon, this would be a strange way to think about meaning. Instead I will be treating meanings as things that are "in here", cognitive entities realized in our brains, depending on our interpretation of what's out there and including imagined entities that aren't "out there" at all (though they are inevitably based on things that are).
I will use function in two senses, first, for the uses that people put language to and second, for the uses that particular words or patterns have within stretches of language. It is the former sense that concerns us here. People use language to refer, to assert, to command, to convince, to get information, to entertain, to deceive, and much more, and these uses of language obviously have something to do with the forms that they choose. (If you want somebody to lend you their computer, you don't say you will lend me your computer, you say something like could I borrow your computer?.)
Many people who study language make a distinction between function in this sense (part of what they call "pragmatics") and meaning (what they may call "semantics"). I would argue instead that the difference is a matter of degree, but that there's not much point in worrying about where the line between pragmatics and semantics is.
A second theme of the book is that language is the way it is in part because of constraints coming from the nature of human biology and human cognition. A constraint is a kind of limitation on what is possible. Consider constraints that come from the nature of the human body itself. For spoken language, the physical and physiological properties of the vocal tract constrain what can be produced, and the auditory system constrains what can be perceived. For sign language, the physical and physiological properties of the hands, arms, upper body, and face constrain what can be produced, and the visual system constrains what can be perceived.
Just as important are cognitive constraints, constraints arising from the nature of the human mind. First, there are limitations on human memory. Cognitive scientists divide human memory into short-term and long-term memory. Short-term memory is used to temporarily store the information that is needed as we interpret the world around us. When we are faced with a complicated visual scene, we can't look at everything at once, and we have to scan the scene in order to come up with some kind of interpretation. But we need to temporarily store some sort of record of what we've already seen in the scene as we do this. That information is kept in short-term memory. Likewise, when we are listening to a sentence, we need to remember the parts that we've already heard as we are trying figure out the meaning of the whole. Short-term memory is used for this as well. The same applies to reading and to the visual processing of sign language. Cognitive science research has shown that our short-term memory has a very restricted capacity, and this places strong constraints on how sentences and discourses are organized.
We use our long-term memory to store information that we learn through experience. Information may remain in long-term memory for a very long time, even indefinitely, and human long-term memory is very large, larger than the memory of any current computer. But long-term memory is still limited. We obviously do not have an infinite memory capacity, and just because we have stored an item in memory doesn't mean we can retrieve it when we need it. We will see later how the finiteness of long-term memory matters for how language works.
Since languages have to be learned, limitations on human learning are obviously also relevant. This is perhaps the most complex and controversial topic of all. Everyone at least agrees that language must be learnable because children obviously learn it. That is, it must be possible to figure out the forms, the functions, the meanings, and the associations between them on the basis of the examples of language that are available to young children. It turns out that coming up with an explanation for how this might happen has proven to be very challenging though.
Speaker Orientation and Hearer Orientation
Finally there are constraints that are specific to the two ways in which language is processed, language production, that is, speaking, writing, and signing, and language comprehension, that is, listening, reading, and interpreting linguistic signs. To simplify matters, I will be referring to a language producer as the Speaker, even though writers and signers as well as speakers proper are intended. And I will be referring to a language comprehender as theHearer, even though readers and sign interpreters as well as hearers proper are included. (To remind ourselves of these distinctions, I will capitalize Speaker and Hearer when they are used in this way.)
For the Speaker, the main constraint is that the production of linguistic forms be easy. It is easier for the Speaker to make relatively few distinctions because the Speaker has to remember what the distinctions are and to make the extra effort to keep things distinct. For example, maintaining the agreement between subject and verb in the present tense in English (the girl sings, the girls sing) requires an effort on the part of the Speaker. What is easy for the Speaker depends in turn on constraints from the body. For example, large movements of the tongue tip are more difficult to execute than short movements, so short movements should be preferred from the Speaker's perspective.
For the Hearer, the main constraint is that linguistic forms that need to be distinguished can be easily distinguished in comprehension. This constraint also depends on the body, specifically the parts of the nervous system that are responsible for hearing (for spoken language) and vision (for written and signed language). For example, if a language contains a large number of homophones, that is, different words which sound the same (such as two, too, and to in English), this may put a burden on the Hearer.
Speaker-oriented constraints and Hearer-oriented constraints often oppose each other; what simplifies things for the Speaker (for example, not making many distinctions) complicates things for the Hearer. We will see many examples in the book of these opposing tendencies.
The opposition of Speaker orientation and Hearer orientation is particularly clear as languages change. Languages change for a variety of reasons — contact with other languages, imperfect learning by children, random fluctuation — but it appears that all languages are always changing. Most of the changes can be seen as either Speaker-oriented or Hearer-oriented. For example, the grammar of a language may become simplified as some suffixes are dropped, a change that seems to result in less work for the Speaker. But the two kinds of trends always balance each other out in the end, and the simplification of the grammar in one way will probably be compensated for by an increase in complexity (from the perspective of the Speaker) somewhere else in the grammar of the language. Otherwise language would fail as a communicative device. These built-in pressures in favor of the Speaker and the Hearer apparently prevent the world's languages from moving in some general overall direction. That is, at least in recent history, it does not appear that languages have generally been getting simpler or more complicated (in any sense of these words) as they evolve.