This feature began with an overview and has covered how five vowels become eight, the law of vowels within words, the difference between phonetic sound and phoneme, and two passages of Onin-ron in the original. To close, let’s grade all of it from today’s vantage point.

The unshaken foundation — Arisaka’s Law

First, Arisaka’s Law is accepted in ancient-Japanese research today as an established regularity. The basic skeleton — that within a single root, the Type B o-column vowel does not coexist with a, u, or the Type A o-column vowel, as seen in the plain-language article — is used as a starting point in research on the structure of Old Japanese roots and on the affiliation of Japanese. Later research has also developed various arguments that discuss this regularity in relation to vowel harmony in other languages.

Leading but unsettled — the eight-vowel theory

The eight-vowel theory, meanwhile, is a leading theory but unsettled. As we saw in the plain-language article, against the view that reads the A/B difference as a difference in the vowel itself, views reading it as a difference in consonants or in surrounding sounds have also been put forward. What the Type B vowels actually sounded like is still debated today. What is certain is that two systems were written separately and that the difference is tied to regularities among vowels such as Arisaka’s Law. To the question Hashimoto Shinkichi had carefully left open, Arisaka gave a strong answer, but not a final one.

As a question, not an answer — Onin-ron

The assessment of Onin-ron (1940) is of a different nature. Against Saussure’s “phoneme = value,” Arisaka set the different view “a phoneme is the currency itself.” And rather than treating a phonemic system as “made from present speakers’ purposes,” he saw it as “an institution inherited from ancestors.” The two claims we read in Close reading 1 and Close reading 2 can’t simply be taken as the standard position of phonology today. In present-day phonology, the stance that attends to the “function” of sound distinctions still holds a large place.

But two insights Arisaka put forward remain important questions even now.

An unshaken foundation Arisaka's Law — within one root, Type B o does not coexist with a, u, or Type A o Leading but unsettled The eight-vowel theory — what the Type B vowels actually were is still debated Remains as a question Onin-ron — "what is a sound?" and "who made a phonemic system?"
The current assessment of Arisaka Hideyo's work. Diagram: ToL

From Hashimoto Shinkichi to Arisaka Hideyo

As we saw in the Hashimoto Shinkichi feature, Hashimoto opened a door to the next generation by sorting out “checkable facts” thoroughly. Beyond that door, Arisaka did two things. One was to find the regularity behind the facts (Arisaka’s Law). The other was to pose the fundamental question of what it means at all to “distinguish sounds.” The former carried the study of ancient Japanese greatly forward; the latter tried to place the study of Japanese sounds on the same ground as debates in world linguistics.

Summary

VerdictSubject
An unshaken foundationArisaka’s Law — within one root, the Type B o-column vowel does not coexist with a, u, or the Type A o-column vowel
Leading but unsettledThe eight-vowel theory — what the Type B vowels actually were is still debated
Remains as a questionOnin-ron — is a phoneme the currency itself, or an institution inherited from ancestors? Its answers aren’t the standard, but its questions are alive
Overall positionBeyond the door Hashimoto opened, did two things: discovered a regularity, and posed a fundamental question

In a nutshell — on top of Hashimoto Shinkichi’s “checkable facts,” Arisaka Hideyo stacked two floors: a regularity and a fundamental question. The former stands as a foundation; the latter lives on with its answer still open.