Three Models for the Description of Language

1 Introduction

1. How does Chomsky view the grammar of a language, by analogy to a scientific theory?
   Like a theory based on finite observations that projects them by general laws to predict new phenomena: a grammar is based on a finite corpus and projects it to an infinite set of grammatical sentences by rules framed in terms of constructs (phonemes, words, phrases).
   • Chomsky, 1956, Three Models for the Description of Language (IRE Transactions on Information Theory), §1
2. What does Chomsky take general linguistic theory to explain?
   How to choose a grammar for each language from a finite corpus; equivalently, the ability of a speaker to produce and understand new sentences, and to reject other new sequences as ungrammatical, on the basis of limited experience.
   • Chomsky, 1956, Three Models for the Description of Language (IRE Transactions on Information Theory), §1
3. What is a “grammar of a language L” in Chomsky’s formal sense?
   A device that produces all of the strings that are sentences of L, and only these. A language is a (finite or infinite) set of finite sentences over a finite alphabet.
   • Chomsky, 1956, Three Models for the Description of Language (IRE Transactions on Information Theory), §1
4. How can clear cases like “John ate a sandwich” vs “Sandwich a ate John” test a linguistic theory?
   A grammar built for a corpus containing neither should project it to include the first and exclude the second. For one language this is a weak test, but for a general theory it is strong, since every language’s clear cases must be handled in a fixed, predetermined manner.
   • Chomsky, 1956, Three Models for the Description of Language (IRE Transactions on Information Theory), §1
5. What three questions does Chomsky ask of any proposed theory of linguistic structure?
   (3) Are there interesting languages (like English) simply outside its range of description? (4) Can it give reasonably simple grammars for all interesting languages? (5) Are those grammars “revealing”: does the structure they assign support semantic analysis and give insight into the use and understanding of language?
   • Chomsky, 1956, Three Models for the Description of Language (IRE Transactions on Information Theory), §1
6. Why must any linguistic theory leave some languages undescribable?
   Grammars must be finite, so any theory makes only countably many grammars available, while there are uncountably many languages (sets of strings).
   • Chomsky, 1956, Three Models for the Description of Language (IRE Transactions on Information Theory), §1