There are two different kinds of double negatives and English actually has both.
E.g. `I can't get no satisfaction` is structurally equivalent to French `ne ... pas`, i.e the second `no` is a reaffirmation, not a negation.
On the other hand `read this unless you're not a developer` is a logical double negation and thus equivalent to `read this if you're a developer`. In practice of course there are usually implied subtleties that make the two not entirely equivalent (the same way synonyms are conceptually interchangeable but may carry different subtext).
EDIT: I can't actually think of any true "double negative" in English that isn't indirect (e.g. `indirect` being synonymous with `not direct` thus `not indirect` being synonymous with `not not direct` and `not not` cancelling itself out). The only direct forms I can think of behave like `not ... no` in my first example, i.e. re-affirmations of the negative rather than double negations.
I think most of the complaints about "double negatives" (where the Rolling Stones line is usually cited as an example) are stylistic preferences or intentional misunderstandings based on arbitrary prescriptions (which are usually based in other languages like Latin that are perceived as "purer" or "more sophisticated").
The phrase for what's going on in that Rolling Stones lyric is "Negative concord" and yes, it's normal in many languages and that includes a lot of non-prestige English variants.
"Ain't nobody got time for that" is clear, likewise "I didn't go nowhere" and "He ain't take nothing from nobody" and when something is not clear ("That ain't nothing" could mean it is, or it is not, something) context usually suffices.
True! But that still falls into what I said about true double negations usually having subtext that justifies their existence. Compare "I don't hate it".
I'd argue that in "I don't not like my hometown" not-liking acts almost as a compound verb, similar to "disliking" (which is just using a Latin prefix to say "not"). Resolving the double negative results in information loss because it omits the subtext (which in this case is the important part of the answer).
In other words, saying "I don't not like my hometown" makes sense because "I don't like my hometown" implies negative emotions (disliking) rather than an absence of positive emotions (liking). The difference could also be conveyed in emphasis ("I don't like my hometown") but this is more subtle and easier to misunderstand.
E.g. `I can't get no satisfaction` is structurally equivalent to French `ne ... pas`, i.e the second `no` is a reaffirmation, not a negation.
On the other hand `read this unless you're not a developer` is a logical double negation and thus equivalent to `read this if you're a developer`. In practice of course there are usually implied subtleties that make the two not entirely equivalent (the same way synonyms are conceptually interchangeable but may carry different subtext).
EDIT: I can't actually think of any true "double negative" in English that isn't indirect (e.g. `indirect` being synonymous with `not direct` thus `not indirect` being synonymous with `not not direct` and `not not` cancelling itself out). The only direct forms I can think of behave like `not ... no` in my first example, i.e. re-affirmations of the negative rather than double negations.
I think most of the complaints about "double negatives" (where the Rolling Stones line is usually cited as an example) are stylistic preferences or intentional misunderstandings based on arbitrary prescriptions (which are usually based in other languages like Latin that are perceived as "purer" or "more sophisticated").