Confusion on the politeness vs. formality terminology

Question

I was reading the "Dictionary of Japanese Grammar" series, and I found the way it uses the term formality vs. politeness contradictory and confusing, so I wanted some clarifications.

Here are some examples:

From the "Basic" volume, page 43:

From the "Advanced" volume, page 35:

In the "Basic" volume, だ is said to be informal, while です is said to be formal. On the other hand, the "Advanced" volume defines だ<->です as a plain<->polite pair, but they both are categorized as informal. To add to the confusion, there is this quote:

Which once again contradicts the chart from the first volume of the series. This is especially confusing, because in every resource that I have read (including the verb conjugation chart at the end of the "Basic" volume), the -ます form is the formal form of a verb.

And it never mentions how all of this fits into the 丁寧語・尊敬語・謙譲語 framework either.

So can anyone help me reconcile these contradictions? Also if possible, can anyone point me to a detailed resource on Japanese formality & politeness and how it fits into the 敬語 framework, preferably in English? I tried to look around, but all of them tends to be really shallow and contains few examples. I liked the in-depth style of DoJG explanations, but the contradictions above plus the fact that they completely excluded 敬語 left me wanting for more.

Answer 1

If these are really from two volumes of the same edition, I have to say this is indeed confusing and misleading. 食べた is perfectly valid in formal articles. As for the terminology, I see the following names most often:

• だ: Plain form (can be formal or informal)
• です: Polite form (usually formal, too)
• (である: Literary/stiff form)

In Japanese, だ/である is called 常体 and です/ます is called 敬体.

Regarding the formality vs politeness, I think formality is easier because English has this distinction, too (child vs kid, yes vs yeah). However, Japanese has two styles even in formal settings.

In formal settings, politeness is a sign of humanity and friendliness, so you need it when you communicate with your business partners and customers. On the other hand, the plain form in formal settings is a sign of dignity, academicity and matter-of-factness, and you use it to write a plain news article, an academic manuscript, a rule book, a Wikipedia article, etc.