Present them both with a grammatical error and you’ll get two different reactions. The grammarian will say “That’s incorrect.” The linguist will say “That’s interesting!” because typically the linguist is interested in almost anything a native speaker says because it may provide a window into the processes or knowledge or brain structures that produced that utterance.
I suffer from both impulses. I studied linguistics but work in the publishing field, which is ruled by the iron hand of copyeditors wielding the Chicago (or AP) Manual of Style.
So when I hear people say, for example…
- Bake potato, can goods, and ice coffee
- Can I come with?
- The garden needs weeded and the lawn needs mowed
…I suffer unbearable internal tension. Part of me thinks language evolves over time and this is a natural process. The other part of me winces and reaches for a red pen.