Definition:
Grammar is the structured system of constraints and patterns governing how meaningful units of a language are combined — encompassing morphology (word structure), syntax (sentence structure), phonology (sound structure), and the interfaces between these components. In linguistics, grammar most often refers to a speaker’s internalized knowledge of these patterns — their unconscious linguistic competence — rather than a prescriptive rulebook. In language pedagogy and popular usage, grammar often refers specifically to morphosyntax (verb conjugation, case marking, word order) and to prescriptive rules about “correct” usage. The acquisition of grammar — how learners build an implicit system from input — is one of the central concerns of second language acquisition research.
In-Depth Explanation
Descriptive vs. Prescriptive Grammar
Descriptive grammar aims to describe how speakers actually use language — their attested constructions, forms, and patterns, including variation across dialects, registers, and speech communities. Linguists are primarily descriptivists.
Prescriptive grammar specifies how speakers should use language according to some authority — a style guide, educational institution, or social standard. Prescriptive rules often lag behind actual usage, treat written formal language as primary, and frequently stigmatize regional or vernacular varieties.
The confusion between these two senses of “grammar” is a persistent source of conflict: linguists observe that “split infinitives” and “sentence-final prepositions” are entirely normal in English grammar (descriptive); prescriptivists may still prohibit them.
Grammar as Mental Knowledge
In the generative tradition (Chomsky), grammar refers to the speaker’s internalized knowledge — the implicit rule system that allows a native speaker to judge grammaticality, parse novel sentences, and distinguish acceptable from unacceptable strings. This mental grammar is unconscious, acquired without formal instruction by all typically developing children, and underlies the productive capacity of language.
Grammar in SLA
L2 learners construct an interlanguage grammar — an evolving implicit system that differs from both L1 and L2 target grammar. Key findings:
- Grammar is acquired in predictable sequences (e.g., morpheme order studies for English)
- Explicit grammar instruction accelerates certain aspects of acquisition but cannot directly install implicit knowledge
- Noticing (Schmidt) is proposed as a prerequisite for conversion from input to intake to acquisition
- Output and interaction push learners to attend to grammatical gaps
Pedagogical Grammar vs. Theoretical Grammar
Pedagogical grammars are designed for learners — they simplify, select, and sequence grammatical content for teaching purposes. Theoretical grammars (generative, functional, typological) aim to capture the full range of syntactic phenomena and explain them within formal or functionally motivated frameworks. Neither purpose entails the other.
Common Misconceptions
“People who make grammatical errors don’t know grammar.” From a linguistic perspective, all native speakers know the grammar of their variety fully. What prescriptive teaching calls “errors” are often attested features of a non-prestige variety, not evidence of ignorance. In SLA, “errors” in the L2 are systematic features of the learner’s interlanguage, not random failures.