What is the difference between ni and ni wa, when talking about a person?

Question

What is the difference between ni and ni wa, when talking about a person?

Ni has many meanings, but it is often used as a marker for direction. Wa is often used as a topic marker.

In my textbook, it has the following example:

Kanojo ni wa takusan no keiken ga arimasu.
She has plenty of experience

Why is ni wa, used for Kanojo (she). How can you have a person as a direction?

There is also this:

Kouhosha erabi ni wa motto sentakushi ga aru beki dato omoimasu.
I think there should be more choice in candidates

Again, ni wa is used for Kouhosha erabi (Candidate selection). Again, how can you have people as direction?

This answer for a similar question, says that ni wa helps to indicate an embedded subject, but I don’t understand how that differs from plain wa on it’s own, and what is gained by using ni wa.

Would the above examples sentences be wrong if they omitted ni? If not, then what does ni add to the meaning? What is the rule for when to use ni wa in place of wa?

Answer 1

Why do you try to stick to only one definition of ni when you already know it has many meanings?

Kanojo ni wa takusan no keiken ga arimasu.
彼女にはたくさんの経験があります。

(lit.) In her, there is much experience.
→ She has a lot of experience.

Here に is used as a place marker. Think of it as "within her" or "in her", and it's actually no different from the 図書館 example you linked. It's the first definition of jisho.org.

Kouhosha erabi ni wa motto sentakushi ga aru beki dato omoimasu.
候補者選びにはもっと選択肢があるべきだと思います。

For choosing a candidate, I think there should be more choices.

Here に is used to mark a purpose, and it's the third definition of jisho.org. 候補者選び is a noun phrase which literally means "candidate-choosing". A simpler example for this に is 買い物に出かける (="go out for shopping").

And these は after に are topic markers, which indicate what they are talking about. I don't know how I can explain this better when you are already seeing good explanations.

Can we omit に or は in these sentences? Without these は, these sentences will look fairly awkward. Presenting a topic is important.

Whether you can drop に before は depends on the sentence. You can safely drop the に without changing the meaning in your second example:

候補者選びはもっと選択肢があるべきだと思います。

This would be closer to "Regarding candidate-choosing, ..." than "For candidate-choosing, ..." but it still makes sense. You can drop に in your first example, too, but it would make the sentence slightly awkward.

Sometimes dropping に can drastically change the meaning of the sentence:

• 彼には感謝しています。 I am grateful to him.
• 彼は感謝しています。 He is grateful (to someone).

Answer 2

I like to think of ni as an all purpose location marker, location of information, location of destination, location of existence, location of receiver, even location of intent, (kaimono o shi ni iku・買い物をしにいく)