Which type of rules governs the arrangement of symbols in a sentence?

Concept: A language is described by several interlocking rule systems, and each system is identified by the level of language it controls. Phonological rules control the sound system, semantic rules control meaning, syntactic rules control the permissible ordering and combination of units into phrases and sentences, and pragmatic rules control appropriate use in a social context. So a rule system is named by asking which level it operates on: sound, meaning, structure or use.

Application: The question asks about the arrangement of symbols within a sentence, that is, which unit may follow which and how the units combine into a complete sentence. Arrangement is a property of structure rather than of sound, meaning or social use, so the system operating here is the syntactic one. Syntax specifies which sequences of symbols form a grammatically acceptable sentence in a language and which do not, and it does so independently of whether the resulting sentence is meaningful.

Cross-check: Each of the other rule systems operates on a different level, and that is what separates it from structure:

• Semantic rules operate on meaning. The sentence "Colourless green ideas sleep furiously" is arranged perfectly well and still says nothing coherent, which shows that structure and meaning are governed separately.

• Phonological rules operate on sound. They decide that a cluster such as "str" may begin an English word while "tsr" may not, and they say nothing about word order.

• Pragmatic rules operate on use. They decide whether "Pass the salt" or "Could you pass the salt, please?" suits the listener and the setting, even though both are arranged in the same grammatical way.

Result: The arrangement of symbols in a sentence is therefore governed by syntactic rules, while the remaining systems govern sound, meaning and use respectively.