Does だ in 予定だ add emphasis?

Question

I thought <noun>+だ at the end of a casual sentence adds emphasis (unlike the constructions where だ is needed for grammatical reasons such んだ, だから, だけど). So when I want to simply share some information in a mild tone, without any emphasis, I end with just <noun>.

However, when I looked up 予定 in 研究社 (in the sense "I'm planning to..."), I saw all the informal sentence examples end with <noun>+だ:

• 土産は帰りに買う予定だ.
• 彼女は, 来月から香港に移り住む予定だ.
• 今日は顔だけ出してすぐ帰る予定だ.

Would it sound natural to say "土産は帰りに買う予定" etc. when no emphasis is intended? Or did I misunderstand the role of だ?

Answer 1

土産は帰りに買う予定だ is something one might write in their personal diary, but it's not something an ordinary person actually says out loud in reality. In ordinary informal conversations, we almost never end a sentence with だ; it's usually too blunt and unfriendly. Instead, we use 買うと思う, 買うつもり, 買う予定, 買おうかな, 買うよ, 買うね, and so on.

However, since conciseness and "compliance to standards" are important for any dictionary, we normally see だ as part of example sentences whenever it's grammatically valid, even though people don't usually say 予定だ in informal sentences. Even です is not suitable as an example in a dictionary because it's one character longer. You have to get used to this fact when using a Japanese dictionary. There are simply too many variations in the way real Japanese sentences can end, and dictionaries have no option but to stick to だ as the shortest and most canonical one.

Answer 2

As others have mentioned, whether to use だ or not is not fundamentally about adding emphasis, that is actually really more a side-effect of various other factors.

In reality, ending with だ is technically simply the complete form of a full casual sentence, and so arguably should be seen as the "standard" construction. It is what most people are taught in textbooks, etc. However, it is the case that in the real world, many speakers, when speaking casually, will just tend to drop the だ in many situations. Because of that, when people would normally leave off the だ but instead choose not to, it can sound more forceful or emphatic as a result.

However, it's also not the case that everyone always leaves off だ when speaking casually either. Whether someone will choose to leave it off or not depends on the situation, and the sentence. In particular, だ is typically omitted most of the time when saying short sentences of only a few words, but it is more common to actually leave it on when speaking longer sentences (I think partly because it can serve as a useful "end of sentence" marker to help the listener sort out more complex sentence grammars).

So in the examples you quoted, because they are longer sentences, ending with だ does not necessarily sound "emphatic", because it's actually more normal to keep it on the end of the sentence in that sort of situation anyway.