Prescription and description
The prescriptivist and descriptivist approaches often clash: the former prescribes how English should be spoken; the latter describes how English is spoken. An extreme prescriptivist might maintain that even if every sentence of actual English used a certain construction, that construction could still be incorrect; and conversely, an extreme descriptivist might maintain that any English sentence that is ever uttered is part of the English language and hence by definition correct.[5] In practice, however, speakers lie between these two extremes, holding that because English changes with time and is governed in large measure by convention, a construction must be considered correct once it is universal, but also that a given sentence can be "incorrect" if it violate the conventions of English.