Do you know what the word ambivalent means?
Or rather they don’t. In fact no one ever gets confused about literally, and no one ever gets confused by double negatives; annoyed, yes, confused, no. What actually happens is some smart arse informs everyone that it is ‘wrong’ and then explains why. The redundancy of this would beggar believe if it wasn’t for the fact it happens daily.
Is there any other area of human endeavour where we so readily assent to be told that we are ‘wrong’? If you baked a cake which tasted delicious and someone told you the way you made it was wrong or, when eating soup, someone sneered at you for lacking an oyster fork or cutting the bread too thickly you would (rightly) think they were either insane or an intolerable bore. Make this kind of ridiculous comment with regards to language and everyone will nod approving and consider you to be a very sophisticated sort.
People get by using double negatives in English all the time. As with all these silly rules, they are of course countless exceptions that the pedants oddly let slide such as “not impossible” or “it’s not that I don’t…”, “it’s not like I don’t want to”. In AAVE double negatives can strengthen a statement such as “I didn’t do nothing”. They also exist in a huge number of the world’s languages and no one gets confused. I have no problem criticizing language that is clearly illogical but this is just pedantry.
If we allow people to dictate language use to us, we end up with the bizarre situation such as the one I heard the other day on “In Our Time“. The situation arose because the speaker used the word ‘decimate’ which has the prefix “dec” meaning “ten” as in December, the 10th month (blame Numa Pompilius for this) and means “destroy one in ten. Most people use it to mean “destroy” because having a word for “destroy one in ten” isn’t that useful. On the show the speaker said, something like “the Romans decimated the enemy, -they literally killed one in ten of the enemy soldiers.” Call me an old cynic but if you need to explain a word after you use it maybe it’s time to admit that the meaning has changed and get on with your life and if you need to explain why something is wrong you probably need to think carefully about your definition of ‘wrong’.