What does it truly mean to “know” a language? Is linguistic knowledge qualitatively different in first-language versus additional-language acquisition?

What does it mean to "know" a language?

To “know” a language is not to possess an abstract rulebook lodged somewhere in the recesses of the mind. Nor is it to have internalised a set of syntactic transformations or parameter settings. Rather, it is to have entrenched a vast network of symbolic pairings — constructions — that link form and meaning, and to be able to deploy them flexibly in situated interaction.

Language knowledge is usage-based and gradient. It emerges from experience. Through repeated exposure to linguistic events, patterns become entrenched; through participation in communicative exchanges, speakers develop sensitivity to subtle distributional cues, pragmatic norms, and sociocultural expectations. To know a language is to have developed a richly structured inventory of constructions — from morphemes to idioms to discourse patterns — interconnected within a dynamic conceptual network.

But this is only half the story.

Because meaning is primary, knowing a language also means having access to the conceptual models that linguistic forms conventionally evoke. These models are grounded in embodied experience and cultural practice. When you know a language, you know not just how to combine forms, but how those forms map onto shared ways of construing the world — ways of profiling events, assigning perspective, expressing stance, managing interpersonal alignment.

In other words, linguistic knowledge is not separable from conceptual and cultural knowledge.

Now, is this knowledge qualitatively different in first-language versus additional-language acquisition? There are important differences — but they are differences of degree and developmental trajectory, not of kind.

First-language acquisition occurs in tandem with conceptual development. The child’s emerging linguistic constructions are co-evolving with perceptual, motor, and social cognition. The conceptual system is being scaffolded in part through language, and vice versa. Entrenchment happens early, rapidly, and largely implicitly. Patterns become deeply routinised, automatised, and integrated into identity and affect.

In additional-language acquisition, by contrast, the learner already possesses a fully elaborated conceptual system shaped by the first language. This has profound consequences. Existing constructions and conceptual mappings can facilitate learning when there is overlap — but they can also constrain it when the target language encodes experience differently. The learner is not building a conceptual system from scratch; they are negotiating between established patterns and new ones.

From this standpoint, additional-language acquisition involves restructuring — sometimes subtly, sometimes dramatically — how one construes experience. It may require adopting new metaphorical mappings, new perspectival habits, new grammaticalised distinctions. For instance, languages differ in how they encode motion, evidentiality, aspect, or spatial relations. Acquiring these patterns is not merely a matter of memorising forms; it is a matter of learning new habitual ways of conceptualising events.

Yet the underlying mechanisms — frequency effects, entrenchment, analogy, categorisation — remain the same. Both first- and additional-language acquisition are driven by usage. Both rely on pattern extraction and the gradual strengthening of symbolic associations. The architecture of learning does not change.

What differs is the cognitive ecology.

In first-language acquisition, language and world knowledge grow together. In additional-language acquisition, new linguistic patterns must find a place within an already entrenched cognitive and linguistic network. That makes the process slower, often more effortful, and sometimes resistant to full automatization — but not fundamentally distinct in kind.

So, to “know” a language, ultimately, is to participate fluently in a community’s patterned ways of meaning-making. It is to have internalised not just a grammar, but a repertoire of embodied, culturally embedded constructions — and to wield them with sensitivity to context, intention, and social consequence.

Language knowledge, in short, is not possession of rules. It is the capacity for meaning construction in interaction.