Generative grammar is an umbrella term for a variety of approaches to linguistics. What unites these approaches is the goal of uncovering the cognitive basis of language by formulating and testing explicit models of humans' subconscious grammatical knowledge.
Cognitive science Generative grammar studies language as part of
cognitive science. Thus, research in the generative tradition involves formulating and testing hypotheses about the mental processes that allow humans to use language. Like other approaches in linguistics, generative grammar engages in
linguistic description rather than
linguistic prescription.
Explicitness and generality Generative grammar proposes models of language consisting of explicit rule systems, which make testable
falsifiable predictions. This is different from
traditional grammar where grammatical patterns are often described more loosely. These models are intended to be parsimonious, capturing generalizations in the data with as few rules as possible. As a result, empirical research in generative linguistics often seeks to identify commonalities between phenomena, and theoretical research seeks to provide them with unified explanations. For example,
Paul Postal observed that English
imperative tag questions obey the same restrictions that second person
future declarative tags do, and proposed that the two constructions are derived from the same underlying structure. This hypothesis was able to explain the restrictions on tags using a single rule. Competence is the collection of subconscious rules that one knows when one knows a language; performance is the system which puts these rules to use. This distinction is related to the broader notion of
Marr's levels used in other cognitive sciences, with competence corresponding to Marr's computational level. For example, generative theories generally provide competence-based explanations for why
English speakers would judge the sentence in (1) as
odd. In these explanations, the sentence would be
ungrammatical because the rules of English only generate sentences where
demonstratives
agree with the
grammatical number of their associated
noun. :(1) *That cats is eating the mouse. By contrast, generative theories generally provide performance-based explanations for the oddness of
center embedding sentences like one in (2). According to such explanations, the grammar of English could in principle generate such sentences, but doing so in practice is so taxing on
working memory that the sentence ends up being
unparsable. :(2) *The cat that the dog that the man fed chased meowed. In general, performance-based explanations deliver a simpler theory of grammar at the cost of additional assumptions about memory and parsing. As a result, the choice between a competence-based explanation and a performance-based explanation for a given phenomenon is not always obvious and can require investigating whether the additional assumptions are supported by independent evidence. For example, while many generative models of syntax explain
island effects by positing constraints within the grammar, it has also been argued that some or all of these constraints are in fact the result of limitations on performance. Non-generative approaches often do not posit any distinction between competence and performance. For instance,
usage-based models of language assume that grammatical patterns arise as the result of usage.
Innateness and universality A major goal of generative research is to figure out which aspects of linguistic competence are innate and which are not. Within generative grammar, it is generally accepted that at least some
domain-specific aspects are innate, and the term "universal grammar" is often used as a placeholder for whichever those turn out to be. The idea that at least some aspects are innate is motivated by
poverty of the stimulus arguments. For example, one famous poverty of the stimulus argument concerns the acquisition of
yes–no questions in English. This argument starts from the observation that children only make mistakes compatible with rules targeting
hierarchical structure even though the examples which they encounter could have been generated by a simpler rule that targets linear order. In other words, children seem to ignore the possibility that the question rule is as simple as "switch the order of the first two words" and immediately jump to alternatives that rearrange
constituents in
tree structures. This is taken as evidence that children are born knowing that grammatical rules involve hierarchical structure, even though they have to figure out what those rules are. The empirical basis of poverty of the stimulus arguments has been challenged by
Geoffrey Pullum and others, leading to back-and-forth debate in the
language acquisition literature. Recent work has also suggested that some
recurrent neural network architectures are able to learn hierarchical structure without an explicit constraint. Within generative grammar, there are a variety of theories about what universal grammar consists of. One notable hypothesis proposed by
Hagit Borer holds that the fundamental syntactic operations are universal and that all variation arises from different
feature-specifications in the
lexicon. On the other hand, a strong hypothesis adopted in some variants of
optimality theory holds that humans are born with a universal set of constraints, and that all variation arises from differences in how these constraints are ranked. In a 2002 paper,
Noam Chomsky,
Marc Hauser and
W. Tecumseh Fitch proposed that universal grammar consists solely of the capacity for hierarchical phrase structure. In day-to-day research, the notion that universal grammar exists motivates analyses in terms of general principles. As much as possible, facts about particular languages are derived from these general principles rather than from language-specific stipulations. == Subfields ==