Linguistics and Lingistic Criticism

Linguistics is the systematic and scientific study of language — either a specific language (such as English), a family of languages (such as Romance languages), or the idea of language in general. ???

From the Guide to Literary Terms by Jack Lynch.
Please send comments to Jack Lynch.
Note: This guide is still in the early stages of development.
Three question marks mean I have to write more on the subject. Bear with me.