The use of adverbs in english

I just realized that I need to get help with understanding how to use adverbs in English. Let's say that a guy is nice, and he performs every action in that way.

Does he:
a) act nice
b) act nicely

Which one is the correct one and why is it so? Don't be afraid to use grammatical terms.

To me "act nice" means that he's consciously being/pretending to be nice, while "act nicely" means what you originally thought it does: performing every action in a nice way. "Act nicely" isn't something native speakers would say, though. They would usually phrase the idea differently.

"Nicely" is only an adverb while "nice" is only an adjective. "He acts nice" or similar examples are idiomatic phrases and are grammatically incorrect regardless of the shades of connotation brought up by >>2

"With niceness (noun) in mind, he nicely (adverb) conducts nice (adjective)acts"

There's not much of a difference to me...
Then again I'm from the Southern US and we aren't unknown for bad grammar...
But I ain't give a fuck

>>3
grammatically incorrect regardless of the shades of connotation brought up by >>2
>>4
There's not much of a difference to me...

Well yeah, colloquial English tends to be grammatically incorrect if you hold a prescriptivist view like >>3 does, but to me it is normal, if dialectal speech. Dropping the -ly ending while still using the word as an adverb is a pretty salient feature of spoken [American] English.

To sum up: act nicely = standard English, act nice = colloquial English.

It doesn't really matter anyway. In one thousand years English will have changed entirely and our arguments about 21st century grammar will look ridiculous.

>>5
Yeah, I know. There's technically no "standard" rules of English (besides what's agreed upon by English teachers and the like who write all the grammar books). We have no equivalent of the Academie Français.
Which is good, it lets the language evolve. I personally like Southern English, ain't and y'all are pretty convenient. Except of course in obvious situations like job interviews where you want to talk in very educated speech. And outside of the south, people will look at you like an idiot for using them...

>>6
This. It probably won't change as much as it has in the past 1000 years, but no doubt it'll be simplified as hell (god forbid we use something similar to ebonics)

>>6
In one thousand years our arguments about 21st century grammar will look ridiculous

Really? Something is ridiculous just because it is outdated? Tell me more.

>>1
Being prescriptive, "act nice" is incorrect - "nice" is an adjective, it modifies substantives, not verbs. In this case, use "nicely".

Being descriptive, yes, -ly particle will fall hard in the next centuries. In 23th century Britanic, Merkinish and Aussish, probably "act nice" will be correct, since "nice" will work both as adjective and adverb.

>>1
The former. Acting nicely means the manner of his acting is nice, which wouldn't make much sense unless you were referring to an actor's ability. You might play nicely or behave nicely.

>>7
Implying ebonics is simplified.

>>10
AY BRUH U GOT DAT ROCK? I BE WHIPPIN SHIT HARD YO GETTIN DAT MONEY FO DEM BISHES AND DAT KUSH YO

It's simplified compared to the English you would use to write your term paper.

>>9
Why learn Bitanic or Aussish? Erryone speaks Merkinish

>>11
It's simplified compared to the English you would use to write your term paper.
Something tells me your definition of "simplified" just consists of "spoken by blacks".

>>11
Everyone will soon speak Merkinish, but we will have several dialects of Merkinish like Brit-Merkanish, Black-Merkenish, South-Merkinish

>>12
implying any dialect spoken by blacks is not going to be simplified

Also I believe they prefer to be called coloreds you fucking racist.

>>1
Well that depends on what you say
"Does he act nice?"
"He acts nicely."

I'm sure someone will argue that the question should be worded "does he act nicely" but to me that sounds like you're asking if his actions are done well, not done politely. Unfortunately English is almost entirely idiomatic and connotations are very important to understand in order to convey the correct message properly with little to no room for error.