Two types of rules govern the use of language. The first type is constitutive rules, which define words’ meanings. Constitutive rules tell you what words “count as” what objects (Searle, 1965). For example, in the English language, dog represents a four-legged domesticated animal that is a common household pet. In Spanish, the word perro represents this same animal. Constitutive rules involving informal or metaphorical expressions can make things challenging when you’re trying to learn a new language. For example, someone new to English may get confused when a friend says, “My dogs are tired,” if the speaker really means, “My feet hurt.”

The second type comprises regulative rules, which control how you use language. Regulative rules guide everything from spelling to grammar to conversational structure. Examples in the English language include “Add an ‘s’ or an ‘es’ to a noun to create its plural form” and “When someone asks you a question, you should answer.”