Why does 好き use な?


If 好き is a noun, then why does it take the な copula in things like 好きなこと? I
thought that copula was reserved for adjectives, and I thought nouns took on
the の copula.




I think 好き was originally a noun derived from 好く, but then it came to be used
as a _na_ -adjective as well. In fact, most _na_ -adjectives derive from nouns
(and some people consider them to _still_ be nouns).

The following quote is from [_Origins of the Verbalizer Affixes in the Japonic
Languages_](http://ling.yale.edu/sites/default/files/files/alumni%20senior%20essays/TylerLAuSeniorEssay.pdf)
by Tyler Lau:

> Uehara (2003) provides a compelling argument for the development of the non-
> inflecting adjective class in Japanese. He claims that this class developed
> from a metaphorical interpretation of container-based locational
> expressions, accompanied by a shift in the semantics of "things" to
> "properties." Uehara observes that **the majority of non-­inflecting
> adjectives can be traced back to regular nouns** and that only a few are of
> unknown origin. _(emphasis added)_

The Uehara paper cited is _A Diachronic Perspective on Prototypicality: The
Case of Nominal Adjectives in Japanese_ (Satoshi Uehara, 2003).

So it's not surprising that 好き looks like a (deverbal) noun. But if you check
[a dictionary](http://kotobank.jp/word/%E5%A5%BD%E3%81%8D), you'll see that
it's marked not only 名 (short for 名詞 "noun"), but also 形動 (short for 形容動詞,
which is the part of speech that corresponds to _na_ -adjective).

So from the perspective of the modern language, it uses な (or だ, etc.) because
it's a _na_ -adjective.

