Language guardians have often blamed linguists as defenders of bad language: moral and cultural relativism is often tossed in at no extra charge. We as a profession are supposedly promoting the idea that anything goes in grammar... But no, we have never said anything goes in grammar. (...) When it comes to the proper use of language, universal grammar is the ultimate authority. It is not about what rules are deemed reasonable or popular; it is about what rules are true. And one sign for a true rule is that it appears in young children, long before they are polluted by dubious grammatical advice.
Charles Yang, The Infinite Gift: How Children Learn and Unlearn the Languages of the World
grammar-nazis, language, universal-grammar