Native speakers of English - or any other language - seem to know how to use their own language, and what is correct in language use, even without formal study of the rules of grammar. People just seem to know "what sounds right". Many very wise people have written about this at length and I wouldn't dare try and compete with Noam Chomsky, Steven Pinker or David Crystal.
Sometimes, as languages grow and develop, confusing situations occur with different meanings or different rules for similar sounding words. While recognising that language changes, we try to pass on these more sophisticated usages as they are keys to subtle yet meaningful variations in our speech and writing. Those of us who love clarity and correctness (and I count myself amongst them) can be upset when distinctions are lost, and this week Chicago Tribune columnist Mary Schmich eloquently bewailed the apparent loss of one distinct variation in usage. The particular distinction that bothered Schmich was the difference between "lie down" and "lay down". This is a distinction that I understood automatically, but I had to go to Michael Swan for a formal explanation. "Lay" means to put down carefully, says Swan, and takes an object. It has a regular form, but an awkward spelling in its past tense ("laid" not "layed"). "Lie", meaning to be or become horizontal, is an irregular verb, with the past tense "lay". It's easy to see how this may confuse some people.
The unhappiness that people like Schmich and I feel when distinctions are lost is not due to us being "old-fashioned", or "conservative", but because we believe that the variety that correct usage entails enriches language, while casual and thoughtless usage makes language poorer for all of us.
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