Study names end in 論 - criteria?

Question

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?

Answer 1

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, 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.