A Concise Guide to English Grammar

One of the most remarkable properties of human language is its productivity (also called creativity or generativity). This refers to our ability to produce and understand sentences we have never encountered before. Right now, you are reading sentences that have almost certainly never been written or spoken before in the history of the world, yet you understand them perfectly well. You could respond with equally novel sentences, and this exchange could continue indefinitely.

This creativity isn’t random—it’s systematic. We don’t produce just any combination of sounds or words; we follow patterns and rules (descriptive rules, that is) that allow us to combine existing elements in novel ways. Language is sometimes described as "infinite use of finite means": from a limited set of sounds, words, and rules, we can generate an unlimited number of sentences.

Sentences can theoretically be infinitely long and still be grammatical. Consider: “This is the cat that chased the mouse that ate the cheese that came from the cow that lived on the farm that Jack built.” We could keep adding clauses forever. In practice, our memory limits how complex sentences can get, but the grammar itself sets no limit.

This infinite capacity rests partly on recursion—the ability to embed structures within structures of the same type. A noun phrase can contain a clause that contains a noun phrase that contains a clause, and so on without end:

No finite list of sentences could capture English; we need rules that generate infinite possibilities.

Language productivity extends to word formation as well. English speakers regularly create new words and understand them immediately. Verbs can be coined from nouns (as when “Google” became “to google”), compounds can be invented on the fly (pandemic puppy, Zoom fatigue, doomscrolling), and affixes can be applied productively to new bases.

Consider how naturally English speakers understand new words:

These words didn’t exist twenty years ago. Some didn’t exist five years ago. Yet English speakers immediately grasp their meaning and their grammatical behavior (which part of speech they are, how to inflect them). This is productivity in action.

Children provide compelling evidence of language productivity. When young children say “goed” instead of “went” or “foots” instead of “feet”, they aren’t making random errors—they’re demonstrating that they’ve extracted the regular patterns of English and can apply them systematically, even to words that happen to be irregular.

These so-called "errors" actually reveal sophisticated rule-learning. A child who says “I runned to the store” has internalized the rule for forming English past tense (add -ed) and is applying it productively. The fact that “run” is irregular (requiring “ran”) is something that must be learned as an exception. Children typically go through three stages: first using the correct irregular form (having heard it), then over-applying the regular rule, and finally mastering the exception. This U-shaped development curve demonstrates that language acquisition isn’t mere mimicry—children are pattern-learning machines who extract rules and apply them creatively.

Language productivity also means that languages constantly change and evolve. New words enter the language (think of selfie, cryptocurrency, doomscrolling, or gaslighting in its new sense), existing words acquire new meanings, and grammatical patterns shift over time. This change is natural and inevitable, a consequence of the creative, generative nature of human language.

Every generation innovates. Shakespeare invented (or first recorded) words like “assassination”, “eyeball”, and “lonely”. More recently, technology has given us (email, blog, tweet). Slang continually refreshes: what was “groovy” became “cool” became “sick” became “fire”. These aren’t corruptions of language—they’re signs of its vitality.

Change happens at all levels. Pronunciations shift (most Americans no longer distinguish “cot” from “caught”). Grammatical patterns evolve (singular “they” for indefinite reference, once stigmatized, is now widely accepted). Meanings drift (“awful” once meant “awe-inspiring”; “nice” once meant “foolish”). Fighting this change is fighting the nature of language itself.