Her book makes a clear distinction between a local language, a national language, and a universal language. A local language is the one you grow up speaking; it may or may not have a writing system. As I understand her argument, a local language in Italy is something like Neapolitan, Calabrese, Sicilian, Venetian—more than a dialect or an accent—a language that outsiders cannot understand; the national language would be Italian. In Japan, local languages include Tohoku-ben, Kansai-ben, Hakata-ben, and more local; the national language is Japanese. A national language Mizumura says "is an elevated form of a local language" and a country like Belgium might have two national languages.
A universal language is one used internationally for science, business, diplomacy, and more. In the middle ages, Latin was a universal language. Today, thanks to British colonial efforts, trade and US strength after WWII, English has become the universal language. More Chinese may speak Mandarin, but "what makes a language 'universal' has nothing to do with how many native speakers there are, and everything to do with how many people use it as their second language . . . What matters is that English is already used and will continue to be used by the greatest number of nonnative speakers in the world." (Italics in the original.)
One of the things this means is that translation becomes far more important than most people realize. If an author writes in her local or national language, her readers are only those who can read it. If an author writes in English, her prospective readers are all over the world, not only in the US, Canada, the UK, Australia, and New Zealand. Many more Japanese are able to read a novel in English than Americans are able to read a novel in Japanese. This suggests that if an ambitious author wants a wide audience, she ought to write in English even though her native language may be Hausa, Tagalog, Tswana, or Tigrinya.
Translation, however, is at best a limited answer to the challenge of literature written in languages other than English. As Mizumura points out "the works that are usually translated into English are those that are both thematically and linguistically the easiest to translate, that often only reinforce the worldview constructed by the English language, and preferably that entertain readers with just the right kind of exoticism." Readers therefore "are not condemned to know that there is thus a perpetual hermeneutic circle—that in interpreting the world, only 'truths' that can be perceived in English exist as 'truths.'"
And machine translating, while clearly improving almost weekly, has real problems with languages remote from English like Japanese and Chinese. In a news article or instruction manual where the meaning rests mostly on the surface, a machine version may be adequate. But in a work of literature where much of the meaning—and pleasure—is in the nuance, the implications, the way words can resonate against one another, machine translation, as I can testify from my own experience, has a long, long way to go. And—sudden thought—by the time it gets there, (which is not a sure thing), it may be useless because English has so overwhelmed all other languages that no one is bothering to write literature in her native language anyway.
Given her interest, Mizumura has much to say about Japanese literature, its remarkable florescence during the late 19th and early 20th centuries (i.e., during the Meiji and Taisho eras) and, in her opinion, its current low state. Indeed, when her book was published in Japan, she was attacked for her judgment: "She talks down about contemporary Japanese literature, when even Americans say it's great!" As if American opinion is the measure of quality.
I found the book fascinating. Anyone interested in language, literature, Japan, or all three can read The Fall of Language in the Age of English profitably. Because most of us tend to think in our native language most of the time, we are usually no more aware of it than a fish is of the water in which it swims. Mizumura helps us consider the medium in which we think and write, what we're doing, and the effect the spread of English is having on the rest of humanity.