Today I want to address a fairly simple question with a not-so-straightforward answer. Why should we care at all about grammatical "correctness?" This post is dedicated to anyone who has ever thought grammar just seemed like one of those tools that over-bearing instructors use to harass unwitting students. Sure, many grammar rules seem trivial at best. For example, does it really matter if I end a sentence with a preposition? Do I really deserve a lower grade for inserting commas where (you say) they don't belong? By whose authority did knowing the difference between "that" and "which" become the standard for testing English competency? The short answer is both "no" and "yes." The most frustrating part for English speakers, both native and non-native alike, is that with no Academie Francaise (French) or Kultusministerium (German) to regulate spelling and grammar, the English language can truly seem like the wild frontier. Time to bring out your dueling pistols.
Instead of worrying about the business of right and wrong, let's think about grammar as a puzzle. Some pieces fit in particular places better than others. But the great part about language is that it is combinative, meaning that the puzzle can be put together many different ways. Particular pieces or words do not always have to go in certain spots. You can start a sentence with a noun, an adverb, or even a twenty-word phrase if you want. By moving things around, you can add emphasis, change direction, or even hide something.
In terms of "right" and "wrong," the most important factor to consider is audience. When you are chatting with friends or family, it matters very little whether you say "who" or "whom" in the appropriate places. They will understand you regardless and are probably more focused on the content of your speech rather than how you say it. In fact, there are some instances where using the grammatically correct word, like "whom," may draw unwanted attention. Your family might think you are trying to talk down to them or, even worse, making fun of them.
Grammar is a puzzle in two ways. You have to string together the words in a way that makes sense logically. But these words and phrases also need to be appropriate for your audience. Slang, contractions, and ungrammatical phrases are great for communicating with friends but not so great at a job interview (unless the job is working for your best friend--if that's the case you probably won't be sitting in a formal interview anyway). Audience awareness is almost just as important as grammar knowledge. In fact, the identity of your audience can even change the grammar rules you will use.
So, does it matter if you end your sentences with a preposition? The short answer is yes, if your audience cares. No, if your audience doesn't. See y'all at the OK Corral.