Study names end in 論 - criteria?


I've noticed that some studies are named with a 論 suffix in Japanese, and
effectively in Korean as well. They are otherwise simply suffixed with 学 in
Chinese and Vietnamese. Compare these examples:

Japanese 宇宙論 vs Chinese 宇宙学 (cosmology)

Japanese 音韻論 vs Chinese 音位学 (phonology)

There are also words like 集合論 (set theory) that are used in both Japanese and
Chinese, but the English translation is more likely to contain "theory".

So I wonder what makes some studies 論 or 学. Do 論-studies involve much more
_theories_ or _suggestions_ , and those _theories_ or _suggestions_ are, well,
prone to being debatable? For instance, phonologists have had different
opinions on the number of phonemes of Japanese, which makes their study
(phonology) the 論 type? And cosmologists only speculate about the Big Bang
theory, and no one has ever witnessed the creation of the universe since we
didn't exist then, which makes cosmology the 論 type? I also wonder why studies
like archeology (考古学) or paleontology (古生物学) are the 学 type, since they surely
involve a lot of theories. We have yet to be able to travel back in time to
confirm what dinosaurs _really_ looked like, haven't we?




While in ordinary speech we use 論 as a suffix roughly means "theory on ~;
argument for ~", in most of academic fields those ideas are conveyed by 理論
e.g. ひも理論 "string theory", 最適性理論 "optimality theory" or プロスペクト理論 "prospect
theory" etc. (except for mathematics, where they seem to use 論 to translate
the term "theory").

In academia, the suffix **学** is used to indicate a (virtually) self-contained
_discipline_ that has a common target, methodology, goal, etc. On the other
hand, **論** is usually a subcategory or application of a certain-学 framework
to a specific concern. _Phonology_ (音韻 **論** ), _syntax_ (統語 **論** ) and
_semantics_ (意味 **論** ) are all branches of _linguistics_ (言語 **学** ); they
share the same interest and only differ in where to research. Phonology also
has its own subcategory such as _accentology_ (アクセント **論** ) or _tonology_ (声調
**論** ). An example which is a bit confusing is _phonetics_ , [usually
considered as a branch of
linguistics](https://linguistics.stackexchange.com/q/180/6743), which is
called 音声 **学** in Japan. I believe this is mostly for historical reasons, but
I've also seen a phonetician say in his book that phonetics should be its own
discipline, independent from linguistics.

**PS**  
Compounded (hyphenated) names based on 学 retain 学 as is: _sociolinguistics_ →
社会言語 **学** , _cultural anthropology_ → 文化人類 **学**.




While in ordinary speech we use 論 as a suffix roughly means "theory on ~;
argument for ~", in most of academic fields those ideas are conveyed by 理論
e.g. ひも理論 "string theory", 最適性理論 "optimality theory" or プロスペクト理論 "prospect
theory" etc. (except for mathematics, where they seem to use 論 to translate
the term "theory").

In academia, the suffix **学** is used to indicate a (virtually) self-contained
_discipline_ that has a common target, methodology, goal, etc. On the other
hand, **論** is usually a subcategory or application of a certain-学 framework
to a specific concern. _Phonology_ (音韻 **論** ), _syntax_ (統語 **論** ) and
_semantics_ (意味 **論** ) are all branches of _linguistics_ (言語 **学** ); they
share the same interest and only differ in where to research. Phonology also
has its own subcategory such as _accentology_ (アクセント **論** ) or _tonology_ (声調
**論** ). An example which is a bit confusing is _phonetics_ , [usually
considered as a branch of
linguistics](https://linguistics.stackexchange.com/q/180/6743), which is
called 音声 **学** in Japan. I believe this is mostly for historical reasons, but
I've also seen a phonetician say in his book that phonetics should be its own
discipline, independent from linguistics.

**PS**  
Compounded (hyphenated) names based on 学 retain 学 as is: _sociolinguistics_ →
社会言語 **学** , _cultural anthropology_ → 文化人類 **学**.

