The foremost property of mental grammar is that it is generative: it allows each speaker to create new words and sentences that have never been spoken before. The mental grammar generates these new words and sentences according to systematic principles that every speaker knows unconsciously.
Probably the most fundamental property of human language is creativity. When we say that human languages are creative, we don’t just mean that you can use them to write beautiful poems and great works of literature.
When we say that human language is creative, we mean a couple of different things:
First, every language can express any possible concept.
That notion might surprise you at first. I often see magazine articles or blog posts that talk about supposedly untranslatable words that exist in other languages but that don’t exist in English. A quick search online leads me to these gems:
Kummerspeck is the German word for excess weight gained from emotional overeating.
In Inuktitut, iktsuarpok is that feeling of anticipation when you’re waiting for someone to show up at your house and you keep going outside to see if they’re there yet.
And in Tagalog, gigil is the word for the urge to squeeze something that is irresistibly cute.
So if you believe that kind of article, it might seem like some concepts are restricted to certain languages. But think about it: Just because English doesn’t have one single word that means “the urge to squeeze something cute” doesn’t mean that English-speakers can’t understand the concept of wanting to squeeze something cute. As soon as I described it using the English phrase “the urge to squeeze something cute” you understood the concept! It just takes more than one word to express it! The same is true of every language: all of the world’s languages can express all concepts.
The other side of the creativity of language is even more interesting. Every language can generate an infinite number of possible new words and sentences.
Every language has a finite set of words in it. A language’s vocabulary might be quite large, but it’s still finite. And every language has a small and finite set of principles for combining those words.
But every language can use that finite vocabulary and that finite set of principles to generate an infinite number of sentences, new sentences every single day.
Likewise, every language has a finite set of sounds and a finite set of principles for combining those sounds. Every language can use those finite resources to generate an infinite number of possible new words in that language.
Because human languages are all capable of generating new words and generating new sentences, we say that human grammar is generative.
Remember that when we use the word “grammar” in linguistics, we’re talking not about the prescriptive rules that your Grade 6 teacher tried to make you follow, but about mental grammar, the things in our minds that all speakers of a language have in common that allow us to understand each other. Mental grammar is generative.
The final, and possibly the most important thing to know about the creativity of language is that it is governed by systematic principles. Every fluent speaker of a language uses systematic principles to combine sounds to form words and to combine words to form sentences. In Essentials of Linguistics, we’ll use the tools of systematic observation to discover what these systematic principles are.