Unlike Noam Chomsky’s ambitious recent work in linguistics, Steven Pinker’s Words and Rules is a popular exposition of scholarly work on language. It succeeds in its aim of conveying a great deal of information in a lively and often humorous style.1 The book has a simple thesis, often repeated:
The ingredients of language are words and rules. Words in the sense of memorized links between sound and meaning; rules in the sense of operations that assemble words into combinations whose meaning can be computed from the meanings of the words and the way they are arranged.
If we assume that “computed” in the quoted passage just means “figured out,” then there is a way of interpreting the thesis in which it could hardly be false, and indeed would not be worth writing a book about. We cannot imagine a full-blown spoken human language that did not have both words and rules in Pinker’s rather special sensesâ€”that is, that did not have both meaningful spoken units and ways of combining them into larger units such as sentences. Clearly you need both. Words without rules are blind, rules without words are empty.
According to another interpretation the thesis is false. Pinker sometimes talks as if words and rules are sufficient to understand sentences. But that is wrong. We understand the word “cut” in the order “Cut the grass” quite differently from the way we understand “cut” in the order “Cut the cake” even though the same word, in his sense, occurs in both. Thus we understand “cut” in the sentences “The barber cut my hair,” “The tailor cut the cloth,” and “The surgeon cut the skin” quite differently because we bring to bear on these sentences a large cultural background knowledge of how things work and how they are done. For the same reason we don’t know how to interpret the sentences “Sally cut the sun” or “Bill cut the mountain” because we have no background knowledge that would determine an interpretation for these sentences.
Notice that in the sentences we do not understand, we have perfectly ordinary words in perfectly ordinary com-binations, but we still have no idea how to interpret the sentences. The point applies throughout our use of language. We understand the same word “healthy” differently in “healthy complexion,” “healthy diet,” and “healthy body” even though the word keeps the same meaning. The point is one that Pinker seems to have missed: the understanding of any sentence requires a set of capacities that go beyond words and rules in his senses of these notions. In any case, whether we interpret his claim as platitudinous or false, he uses it as an entering wedge into a number of important arguments, as we will see.
One quibble about the title Words and Rules, and the formulation of the thesis: it is misleading for Pinker to treat words and rules as if they were somehow contrasting, because words are also a matter of rules. To know the meaning of a word is, on his own account, to know the rule that associates a sound with a meaning. If I know the meaning of the word “rose,” for example, I know a rule that associates the sound roz with its meaning. And such rules are just as much rules as the rule that says you can form the past tense in English by adding -ed to the verb stem. So, contrary to its title, the book is not about words and rules, but about rules and rules, rules for using words and rules for combining words. Pinker, of course, knows all of this and knows that his contrast is actually between two kinds of rules, which we might think of as particular and general. The rule for forming the past tense in English is general. It says, “For all x if x is a regular verb, form the past tense by adding -ed to the verb stem.” The rule that associates a sound with a meaning is not in that way general. But both types of rules are rules.
If the point that in a language you require at least meaningful elements such as words and rules for combining them into sentences is so obvious, then what is the point of Pinker’s book? His thesis is less trivial when put in the form that language consists of memorized words, each an arbitrary pairing between a sound and a meaning, and a set of rules that assemble words into combinations that give us a potentially infinite number of longer expressions such as sentences. Pinker has important theoretical points to make, and the discussion of “words and rules” is a device for getting at these larger issues. The main point he is making is that there are two quite distinct cognitive operations involved in knowing and using a language: memorization and retrieval of specific cases, “words,” and application of general procedures, “rules.”
He thinks that a good test case for his theory that there are two distinct sorts of linguistic mechanisms is in English irregular verbs, of which there are nearly two hundred. For these verbs we cannot just apply the general rule but must memorize the irregular forms. Once the child knows that the past of walk is walked and the past of stop is stopped, the rule he has learned will not apply to the combinations eat-ate, go-went, ring-rang, blow-blew, is-was, and strike-struck. The rule for forming the past tense in English is wonderfully simple: add -ed. This can receive three different pronunciations, t, d, and id, as in worked, bored, and wanted. There are not three different past-tense rules but one past-tense rule with three different pronunciation (phonological) rules. The irregular verbs seem puzzling because they do not seem to be cases of general rules, but at the same time in many cases they exhibit the features of general rules. Some sets of irregular verbs, for example, come in patterns, thus deal-dealt, feel-felt, and mean-meant as well as write-wrote, drive-drove, and ride-rode and also blow-blew, grow-grew, know-knew, and throw-threw. Furthermore, some of these patterns are productive in the sense that a new verb may be treated as part of the irregular pattern and not given the regular conjugation. Thus if we invent the verb “to spling” and ask ourselves how we would describe someone of whom this verb was true in the past, would we say “he splinged”? Pinker cites studies that show that most speakers prefer “he splung” or “he splang,” on analogy with ring-rang, sing-sang, and wring-wrung.
But if both the regular and irregular past tense involve patterns that people can generalize, then what is the force of Pinker’s distinction between rules and words? His answer is that the irregular patterns involve memorized words and new forms that are similar to the memorized forms. But, he also writes, the regular past tense can apply intelligibly to any word whatever and does not require memorization of a particular word or word pattern. If a child says drived or rided for the past tense, we know what he means. This suggests that there is a psychological and neurobiological distinction between the two sorts of cases. The regular inflection is the normal or default case.
The difficulty with Pinker’s appeal to “patterns” is that it looks like an appeal to certain sorts of rules. Each “pattern” exhibits a rule. If that is the right way to think of the matter, then in addition to the difference between particular and general rules we would need rules that apply to families of resembling cases, as in the examples know-knew, blow-blew, grow-grew. I will come back to this point in a moment.
The reason it is impossible to specify the number of irregular verbs exactly is that old irregulars sometimes become regular and new irregular forms are created. Thus if you think the past tense of thrive is thrived, as I do, then the old irregular form throve has ceased for you, and the verb is now a regular verb. On the other hand, if you are comfortable with the past tense of the verb sneak as snuck, then this verb is an irregular for you, and you part company with those who prefer sneaked.
In an important argument Pinker shows that the notion “regular” does not mean statistically more common. The notion of the regular case does not imply that this case is more frequent. Even in a language where most verbs are irregular there would still be a logical distinction between the regular and irregular forms. The distinction is between those cases where the rule can apply to any word in a category and those cases where you must store in your memory a specific word or a pattern. Of the thousand most common verbs in English, 86 percent are regular, but in German only 45 percent of the thousand most common verbs are regular.
Pinker’s hypothesis about particular rules and general rules is important for him because it leads into much larger questions about human cognition. Three of these are especially interesting.
First, the different logical character of the particular and the general suggests that different cognitive abilities and indeed different parts of the brain are involved in the two sorts of abilities. Studies of brain-damaged patients suggest that this is so. One can have damage to the capacity for memorizing words, without hurting the capacity to apply rules. Pinker’s account here is the most intellectually important part of his book. Recent technological advances in brain imaging, especially functional magnetic resonance imaging (fMRI), can give us information about which structures in the brain are processing which information. The good news, Pinker tells us, is that some recent studies show that different parts of the brain are activated for words and rules, in his special sense of these notions. The bad news is that the different research teams do not agree on which parts of the brain are activated by each process. Much of the importance of this work derives from the fact that if he is right then Noam Chomsky is wrong to think of language competence as a distinct faculty in the brain.
The question is not essentially one of anatomy. It is not whether there is a single location in the brain for the language faculty or two different locations. The question is rather a functional question. Is there one set of functions performed by the brain, or are there two distinct sets of functions? According to Pinker’s theory there are two quite different faculties, and they differ both anatomically and in the principles of their operation. This issue is still very much in doubt. Some work by the linguistic scholar Charles Yang attempts to show how the child could acquire both the regular and the irregular verb conjugations using a single mechanism that assigns probability weights to hypotheses on the basis of linguistic evidence from the environment. According to Yang, many of today’s irregular verbs are historical survivors of what were once systematic rules. There was a rule that produced a past -ew whenever -ow occurred in the present, as in know-knew, blow-blew, and grow-grew. By neglecting this historical evidence Pinker mistakenly supposes that the irregular cases have to be memorized on a case-by-case basis, whereas according to Yang what has to be memorized is which rule applies. Yang strengthens his argument by bringing in evidence from other languages. For example, Yang accepts Pinker’s argument that the “default” or “regular” way to form a plural noun in German is add -s, as in Kinos (cinema) and Autos. This way of forming the plural is statistically rare, but it is regular in the sense that if you don’t know anything else about the word, if it is a new word for example, you can form the plural by adding -s. That explains why many of the examples are of foreign origin. But there are several irregular ways to form the plural, as in Kind-Kinder (child-children), Strasse- Strassen (street-streets), and Hund-Hunde (dog-dogs). Yang argues that these irregular patterns are rule-based and that the child’s task is not to memorize plurals on a word-by-word basis, but to figure out which rule applies, to which set the noun belongs. If Yang is right, and I think he is, then Pinker’s irregulars are not illustrations of the words-and-rules thesis, but the less-general-rules-and-more-general-rules thesis.2
Charles D. Yang, Knowledge and Learning in Natural Language (unpublished Ph.D. thesis, MIT); and "Dig-Dug, Think-Thunk," a review of Pinker in the London Review of Books, August 24, 2000.↩
Charles D. Yang, Knowledge and Learning in Natural Language (unpublished Ph.D. thesis, MIT); and “Dig-Dug, Think-Thunk,” a review of Pinker in the London Review of Books, August 24, 2000.↩