1.1 Language, Grammar and Linguistic Theory
So, presumably, what we have in our heads is a (finite) set of rules which tell us how to recognise the infinite number of expressions that constitute the language that we speak. We might refer to this set of rules as a grammar, though there are some linguists who would like to separate the actual set of rules existing inside a speaker’s head from the linguist’s guess of what these rules are. To these linguists a grammar is a linguistic hypothesis (to use a more impressive term than ‘guess’) and what is inside the speaker’s head IS language, i.e. the object of study for linguistics. We can distinguish two notions of language from this perspective: the language which is internal to the mind, call it I-language, which consists of a finite system and is what linguists try to model with grammars; and the language which is external to the speaker, E-language, which is the infinite set of expressions defined by the I-language that linguists take data from when formulating their grammars. We can envisage this as the following:
1.2.1 The Lexicon
Part of linguistic knowledge, therefore, is a matter of knowing brute fact. For each and every word of the language we speak it must be the case that we know how they are pronounced and what they mean. But this is different from our knowledge of sentences. For one thing, there are only a finite number of words in any given language and each speaker will normally operate with only a proportion of the total set of words that may be considered to belong to the language. Therefore, it is not problematic to assume that knowledge of words is just simply stored in our heads. Moreover, although it is possible, indeed it is fairly common, for new words to enter a language, it is usually impossible to know what a new word might mean without explicitly being told. For example, unless you had been told, it is not possible to know that the word wuthering found in the title of the novel by Emily Brontë is a Yorkshire word referring to the noise that a strong wind makes. With sentences, on the other hand, we know what they mean on first hearing without prior explanation. Thus, knowledge of words and knowledge of sentences seem to be two different things: knowledge of words is brute knowledge while knowledge of sentences involves knowing a system that enables us to produce and understand an infinite number of them (an I-language). Clearly, part of knowing what a sentence means involves knowing what the words that constitute it mean, but this is not everything: the meanings of the words three, two, dogs, cats, and bit simply do not add up to the meaning of the sentence three dogs bit two cats (if you think about it this sentence might mean that anything between two and six cats got bitten, which is not predictable from the meaning of the words).
1.2.1 The Lexicon
Let us assume that these different types of linguistic knowledge are separate. We can call the part of I-language which is to do with words the Lexicon. This might be imagined as a kind of mental dictionary in which we store specific information about all the words that we use: how they are pronounced, what they mean, etc.
2.1.1 The building blocks of sentences
This rule defines sentences in terms of sentences and so the definition refers to what is being defined. A rule that does this is known as recursive, and recursive rules have exactly the property that we want to be able to define human languages. Recall from the discussion in Chapter 1, human languages are limitless and yet they must be defined by a finite set of rules as the human head can only store a finite amount of information. If I-languages are made up of recursive rules, then a finite set of these will be capable of defining an infinite number of expressions that make up an E-language.
Therefore it would appear that clauses are exocentric constructions, having no heads, and as such stand outside of the X-bar system. Later in this book, we will challenge this traditional conclusion and claim that clauses do indeed have heads, though the head is neither the subject nor the VP. From this perspective, X-bar theory is a completely general theory applying to all constructions of the language and given that X-bar theory consists of just three rules it does indeed seem that I-language principles are a lot simpler than observation of E-language phenomena would tend to suggest.