Final answer:
Noam Chomsky argued that all languages share a common structural basis known as universal grammar, which is distinct from the Sapir-Whorf hypothesis on linguistic relativity.
Step-by-step explanation:
The linguist who argued that all languages have a common structural basis or universal grammar is A. Noam Chomsky. Chomsky introduced the concept of a universal grammar, which suggests that underlying all human languages is a common structural foundation. This idea opposes the Sapir-Whorf hypothesis, which postulates that the language we speak influences our perception of reality and thus encourages different habits of thought. Chomsky's perspective was part of a broader critique of the behaviorist approach to language learning, advocating instead that humans have an innate capacity for language acquisition, embodied in what he termed a Language Acquisition Device (LAD).