Negative of ~そうだ

There seems to be conflicting views on the negative form of ~そうだ,

This says that the negative of 帰れそうだ is 帰れそうにない, and that 帰れなそうだ is grammatically wrong. This is what I was taught too.


This says that the negative of 降りそうだ is 降らなそうだ, and that 降らなさそうだ is grammatically wrong (addition of さ correct for adjectives only), and they quoted from NHK website.

So, which grammar Nazi is correct?

The first site is wrong and the second one is correct. そうだ can be attached to the negative form of verbs (-nai stem of verbs + なそうだ). "- masu stem of verb + そうにない" is preffered in formal situation since "-nai stem of verbs + なそうだ" sounds more colloquial.


As in the first site says

ただし、最近は、おっしゃるように「帰れなさそうだ」や「雨が降らなさそうだ」も言えるという日本人が増えてきていることも事実です。,

"-nai stem of verbs + なさそうだ" is indeed actually used. I think しなさそうだ is more common than しなそうだ for the negative of する, including -suru verbs.

So can I say that the difference between そうにない and な(さ)そうだ is similar to the difference between 来られる and 来れる? People understand and use な(さ)そうだ/来れる in everyday speech, but from a strict academic point-of-view, only そうにない/来られる is correct? My sensei probably has a strict academic point-of-view; she'll stare at you if you said 8時ぐらい instead of 8時ごろ.

"-Nai stem of verbs + なさそうだ" is indeed close to ら抜き言葉 such like 来れる. They are both considered grammatically wrong, but actually commonly used in daily life, especially しなさそうだ.

However, "-nai stem of verbs + なそうだ, "stem of na-adjectives + では/じゃなさそうだ" and "-ku form of i-adjectives なさそうだ" are all grammatically correct, as the second site says. The first site says 様態の助動詞「そうだ」は、…助動詞に付くことはできません。and 「帰れなそうだ」は、文法的には誤りということになります。, but these are wrong. な（さ）そうだ just sounds more colloquial than そうにない.