Object of a sentence ambiguity

Question

The sentence: 守りたいのはあなた

This sentence can either mean "The one I want to protect is you" or it can mean "the one who wants to protect (someone else) is you". Any way to distinguish besides context?

Answer 1

This sentence can either mean "The one I want to protect is you" or it can mean "the one who wants to protect (someone else) is you".

Yes, it can mean both.

Any way to distinguish besides context?

No, there is no way to distinguish besides context. But when you write a sentence like this, you can simply add a が-/を-phrase to disambiguate. When a が-marked phrase is already present before のは, あなた will be automatically interpreted as the object.

• 僕が守りたいのはあなた。
  It's you who I want to protect.
• 彼を守りたいのはあなた。
  It's you who wants to protect him.

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Your sentence is a cleft sentence, but 守りたいあなた is already ambiguous. There are many similar questions:

• Clarification about how 惚れた should be translated
• Relative Clause Ambiguous
• The meaning of ”あれは魔術師に与えられた祝福”
• が in subordinate clauses

For example 惚れたのは君だ means both "It's you who fell in love [to me]" and "It's you who [I] fell in love to". 好きなのは彼女だ means both "She loves [him]" and "[He] loves her".