One of the two guiding principles of cognitive approaches to grammar. The symbolic thesis holds that the fundamental unit of grammar is a form meaning pairing, a linguistic unit (called a symbolic assembly in Langacker's cognitive grammar or a construction (1) in construction grammars ). This is at odds with the 'words and rules' approach to grammar adopted in formal linguistics.

By adopting the symbolic thesis, cognitive approaches to grammar are not restricted to investigating aspects of grammatical structure independently of meaning, as is often the case in formal linguistics. Instead, cognitive approaches to grammar encompass the entire inventory of linguistic units defined as form-meaning pairings.

These run the gamut from skeletal syntactic configurations such as the ditransitive construction (expressed in John baked Mary a cake) to idioms (like kick the bucket), to bound morphemes like the -er suffix, to words. This entails that the modular approach towards language and the mind cannot be meaningfully upheld within cognitive linguistics where the boundary between cognitive semantics and cognitive approaches to grammar is less clearly defined. Instead, meaning and grammar are seen as mutually interdependent and complementary.