Prescriptivism and descriptivism

Prescriptivism 

Prescriptivism is a set of rules that govern one variety, or manner, of speaking against another. It implies a view that some forms of language are incorrect, improper, lack communicative effect and are of a low aesthetic value. It deals with the syntax and word structures of a language and is intended as an aid to the learning of that particular language. Prescriptive grammar refers to the structure of a language as people believe it should be used. The opposition to these views is descriptivism.

According to the likes of David Crystal, prescriptive grammar is a manual that focuses on constructions where usage is divided and it lays down rules that govern the socially correct use of language. 

So who supports the theory of prescriptivism?
- Lynne Truss
- Geoffrey Nunberg
- Shadya Cole
- John Honey

Descriptivism 
It is the belief that description is more significant or important to teach, study, and practice than prescription. It's a non judgemental approach to language and focuses on how it is actually spoken or written and allows the native language of people to flourish. The Urban Dictionary is a prime example of the use of descriptivism as it is open to input from anyone and can explore the different interpretations people have for certain words and/or phrases.

So who supports the theory of descriptivism?
- Alexandra D'arcy
- Naom Chomsky
- David Crystal
- Jean Aitchison

David Crystal
Crystal's perspective on language is clear, he is a descriptivist and went as far as creating his own theory on this aspect of language. Tide metaphor, the name of his theory, suggests that language is like a tide. It constantly changes, ebbing and flowing bringing with it a new selection of words and taking out others in a natural and progressive way. He claims that the changes are not for the worse or for the better but that it simply "just changes".