Passive or active object?

Question

The sentence inu ga suki is translated as I like dogs. But why don't we translate it as Dogs like ... (something/someone)? For example, for a question Who likes meat? we can answer inu ga suki.

Answer 1

It is an ambiguity in Japanese.

I like dogs.

=watashi wa inu ga suki.

=inu ga suki. (The subject can be abbreviated if it is clear in the context.)

Who likes meat?

inu ga niku wo suki.

=inu ga suki. (the short version)

So you're correct that two interpretations are possible. You should decide according to the context.

Answer 2

This isn't really about passive-voice. Japanese passive voice has a special conjugation ～られる。 You can find more about this conjugation here. Note that the link I just copied also talks about causative form as well. Passive can be found further down the page.

In this case, what we see here is more of a difficulty understanding what the subject of a sentence really is.

犬｛いぬ｝が好｛す｝きです。(inu ga suki desu.)

Is usually translated as I like dogs, yes, but there are other translations for it as well. It all depends on context. The subject is implied. Here's an example:

お父｛とう｝さんはなにがすきですか？(otousan wa nani ga suki desu ka?)

What does you dad like?

犬｛いぬ｝が好｛す｝きです。(inu ga suki desu.)

He likes dogs.

Here we have the exact same sentence, inu ga suki desu but the translation is diferent (He likes dogs). Why is that? Simply put, the subject of the sentence is implied. You have not specifically designated the subject in this sentence, you have only stated what is liked (dogs).

If we wanted to say I like dogs without any ambiguity or potential for misunderstanding, we would say:

わたしは犬｛いぬ｝が好｛す｝きです。(watashi wa inu ga suki desu.)

I like dogs.

Here, we have an established topic. It can never be confused who likes dogs. (I do!)

This really hits on the diference between は and が、and I suggest that you read up on the difference here.

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So how do you say that the dog likes something? We simply make the dog the subject of the sentence!

Your example sentence might sound a little weird to Japanese ears because dogs don't fall under the expected replies for who. Instead, I'll change it a little bit so it is more natural sounding.

A:あの犬｛いぬ｝はお肉{にく}がすきですか？(ano inu wa oniku ga suki desu ka?)

A: Does that dog over there like meat?

B:分｛わ｝からないけど、お肉｛にく｝がすきでしょう。(wakaranai kedo oniku ga suki deshou.) (Case 1)

B: I don't know for sure, but it probably does like meat.

Dog devours meat.

A:やっぱり、あの犬｛いぬ｝はお肉｛にく｝が好｛す｝きだ。(yappari, ano inu wa oniku ga suki da.) (Case 2)

A: Just as I expected, that dog does like meat.

In case 1, we say that the dog probably likes meat. Notice that we didn't even say inu in the sentence. This is because the topic (dog) is implied, and therefore does not need to be said for the sentence to make sense. Given the right context, that same sentence could come to mean: he probably likes meat, or she probably likes meat. However, since it's established that we're talking about the dog here, it means: the dog probably likes meat.

In case 2 we are saying that the dog does like meat. Here the dog is re-established as the subject of the sentence when we say inu wa...

Long story short, here's the structure of how to say (subject) likes (something):

(subject)は(something)がすきです。

(subject) wa (something) ga suki desu.