The central event in the evolution of language was not the rise of syntax but the emergence of a modern lexicon, words with properties “typical of any human language,” linguist Derek Bickerton told the Evolang conference in Barcelona this morning (Saturday March 15, 2008). The presentation was offered as a rejection to an oft-rebutted, but still influential paper, by Marc Hauser, Noam Chomsky, and Tecumseh Fitch on “The Faculty of Language” (available here). In its place, Bickerton championed Terrence Deacon’s work that asserts symbolic units are unique to humans and that aspects of the lexicon are genuine human universals.
Human words, Bickerton said, are profoundly unlike the signals used by other animals because they are not complete in themselves and they have special relations, both positive and negative, with other words. For example, a word like leopard means very little by itself and if suddenly said in a neutral tone will merely cause confusion. What about a leopard? So the word has to be combined with others, but not every word can be used. Human words have semantic properties (e.g., a leopard can run but not rust), categorical properties (e.g., leopards can be used as subjects or objects, but not as verbs), and grammatical (e.g., a leopard must be pluralized with an –s). Words are meaningless unless they are combined into units that are based on those properties.
Words are assembled into meaningful combinations through a process of indefinite iteration, or a theoretically endless repetition of identical steps. This simplest kind of iteration generates a long string of sentences linked by conjunctions:
The leopard ran after me and I was afraid and I started to run but the leopard was too fast and the leopard would have caught me except for a hunter who thought fast and the hunter shot the leopard so I was saved.
Anybody who has ever taught seventh grade will recognize that style of expression. Linguists will notice something else: this type of speech can be generated by a process called Merge (see: Chomsky’s Theory of Language Origins for an explanation of the process). Bickerton argued that all Merge operations, including those that generate more elegantly complex sentences (e.g., A fast-thinking hunter saved me by shooting a leopard that was chasing me) can be generated through a process of iteration, and do not, as Hauser-Chomsky-Fitch insist, require recursion. Iteration and recursion are both mathematical concepts and their difference is subtle because both concern repetitive processes.
Iteration: partial results from an identical process combine to form a full result: A and B and C and D
Recursion: preliminary results from a context-dependent process are reworked to form a final result: A+B+C+D becomes DB+CA.
Bickerton argues that iteration will suffice to generate even sentences that are commonly taken as self-evidently recursive like Bill thinks that Mary said that John liked her. His argument is too technical to be repeated here, but those interested can find his analysis on line (here).
Bickerton maintained that from the beginning, back in the 1950s, Chomsky has been wholly committed to two ideas: (1) that language is unique to humans and (2) syntax is language’s central element. Well before the beginning of this century, however, It had become apparent that many of the intellectual elements underpinning human language support other animal activities as well. Bickerton says Chomsky came to a fork in the road where he had to abandon either the claim of human uniqueness or syntax’s centrality. Instead of choosing, however, Chomsky tried cutting himself a new path by insisting that the decisive difference between human language and animal communications is not the broad understanding common to both groups, but the narrow capacity that enables humans to generate sentences through a process of recursion. If Bickerton’s analysis is accepted, Chomsky's new path leads nowhere and at least one of his two primal commitments must fall.
Bickerton made clear that he does not think his argument subverts the notion that language is unique to humans. The uniqueness, however, comes from the lexicon and its requirements. Those who are less committed than Chomsky to syntax’s centrality will have an easier time accepting the claim.