Why are conflicting verb tenses allowed in usage of なら

Question

In https://japanesetest4you.com/japanese-language-proficiency-test-jlpt-n4-grammar-exercise-7/ I encountered the following sentence:

父は何でも作れたんだ。

戸棚が必要なら、父が作ってくれた。

If I were to translate this into English, I'm guessing it would be

Father could make anything.

If I need a cupboard, father would have made it for me.

Notice I internally translated as need instead of needed because it was 〜が必要なら and not 〜が必要だったなら.

Similarly, I internally translated as would have made because of the past form in the phrase 作ってくれた.

Looking at my internal translation, however, I end up getting confused because of the divergence of tenses. Surely, the sentence would have been better translated as:

• If I need a cupboard, father would make it for me.

or

• If I needed a cupboard, father would have made one for me.

In other words, perhaps the sentence could have been:

戸棚が必要なら、父が作ってくれるだろう。

In essence, I'm perhaps not understanding how tenses are evaluated. So what did the sentence actually mean? How am I supposed to interpret it correctly?

Answer 1

Your sentence simply means:

戸棚が必要なら、父が作ってくれた。
When(ever) a cupboard was necessary, Father made it (for me/us).

However, if the context so far clearly indicates the cupboard never existed, the following "counterfactual" or "subjunctive" interpretation is also possible (のに can be used for clarity).

戸棚が必要なら、父が作ってくれた(のに)。
If a cupboard is/was necessary, Father would have made it! (counterfactual)

Related: How to express the subjunctive mood in Japanese

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I think なら is a tense-less expression; it's interchangeable with 必要であるなら or 必要だったなら/必要であったなら depending on the subsequent context.

• 今すぐ必要なら、持って行ってください。
  = 今すぐ必要であるなら、持っていってください。
  If you need it right now, take it.
• 明日必要なら、言ってください。
  = 明日必要であるなら、言ってください。
  If you will need it tomorrow, tell me so.
• その時必要なら、なぜそう言わなかったの？
  = その時必要だったなら、なぜそう言わなかったの？
  If you needed it at that time, why didn't you say so?

You can use なら with a noun, in which case なら is clearly tense-less:

• iPhoneならできるようになります。
  It will be possible with an iPhone.
• iPhoneならできます。
  It's possible with an iPhone.
• iPhoneならできた。
  I was able to do it with an iPhone. / I managed to do it with an iPhone. (factual)
  I could have done it with an iPhone. (counterfactual)