The following bolded items are linguistic facts that everyone in the world should be familiar with. (Rosina Lippi-Green’s Linguistic Facts of Life)
All spoken language changes over time.
Implication: You cannot prescribe rules written a century ago to English as it exists today. Additionally, this natural process of change does not mean that the English language is “dying” or “going to shit” or any of those other quaint colloquialisms.
All spoken languages are equal in linguistic terms.
Implication: It is WRONG to judge someone based on how they speak because it is WRONG to consider one language or dialect as subordinate to another. All dialects and languages are inherently linguistically equal. They all function in their own ways, however it may appear to you as a speaker of your own dialect. (Yeah, you speak a dialect of English.) Examples of languages and dialects include Tidewater English, African American English varieties, Boston English, DC-Metro Hispanic English, and standard English varieties.
Grammatical and communicative effectiveness are distinct and separate issues.
Implication: Grammatical “correctness” and effectiveness of speech are separate. If an utterance has grammatical errors based on a standard English variety but is perfectly comprehensible, it is not an incorrect sentence. I’m struggling to explain this one so I welcome emails or comments with questions. I’ll try an example: “That’s what him said.” In many English dialects this is considered hard on the ears, but the listener still understands the message. Therefore it is not wrong. In a dialect other than your own it may be the norm.
Written language and spoken language are historically, structurally, and functionally fundamentally different creatures.
Implication: Prescribing the laws of written language to the spoken word is not only a misled intention, but it’s impossible. Try pronouncing the G at the end of every -ing verb. Furthermore, language is biologically inherent to all humans, whereas writing is a learned skill. Human groups in isolation will develop speech of their own accord but not writing.
Variation is intrinsic to all spoken language at every level.
Implication: VARIATION IS THE NORM. NOT THE EXCEPTION. Keep this in mind as you communicate with anyone ever.