grammar - Problems with は and が

Consider:

[A] 猫が好きだ

To me this means [A']"I like cats."

Contrast this to:

[B] 猫は好きだ

To me this means [B']"I like cats (among other animals)"

I based my understanding of [B] from Derek Schaab's answer to "What is the difference between “に” and “には”?":

You'll see that while in the first sentence there is only one scope, the second actually has two:

(私【わたし】は）彼【かれ】と会【あ】わなかった。

• Scope (implied): I


• Statement: Didn't meet with him.

(私【わたし】は）彼【かれ】とは会【あ】わなかった。

• Outer scope (implied): I


• Inner scope (explicit): with him


• Statement: Didn't meet.

Now as for what effect this has, the は often adds a hint of comparison or contrast, as repecmps mentioned. While both of the above sentences translate to, "I didn't meet with him," the second hints that although you didn't meet with him, you may have met with someone else.

So I deduced that は in [B] can perform that disambiguative role.

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Now [A] can be interpreted to mean "I like cats" because of the implicit first person as in (私は)猫が好きだ

Now let's make 私 explicit:

[C]私は猫が好きだ - [C']"I like cats"

Now it is explicit that I am doing the liking.

Now reconsider [B]猫は好きだ:

Based on [C], I have another way to interpret [B]:

So now 猫は好きだ can mean [B'']"The cat likes (an unspecified object)"

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(Questions) What is going on? Who is doing the liking and who is being liked in each case? Are [B'] and [B''] both valid? What am I doing and understanding wrong? If there is indeed ambiguity, how can I resolve it?

EDIT:

Can I resolve it by introducing another は element? E.g.

私は猫は好きです。 "I(thematic) like cats(disambiguated/anaphoric)"

Is it acceptable to have two はs in a sentence as above?

Answer

私は猫が好きだ means I like cats.

私は猫は好きだ has the same meaning and it's absolutely possible.

But in the second case you are putting emphasis on what you like for whatever reason: maybe you are going to talk then about cats, or you want to remark that you like a specific cat (私はこの猫は好きだ), or want to focus attention on cats, etc.

The same emphasis can be put on other subjects marked with が.

ドアが開いています。
このドアは開いています。

Direct object can be marked with は instead of を for the same reason.