When do you use するには as opposed to するため（には） to mean "in order to"?

Question

I keep having するため（には） corrected to するには when writing sentences, but how interchangeable are they and when should each be used?

Taking some Japanese sentences from Space ALC with my own English translations, is there some reason why one or the other is more natural/correct than the other in these examples for instance?

• 仕事で成功するには、家で、喜んで私を助けてくれる夫が必要なのです。
  In order to succeed at my job, at home, it's essential for there to be a husband who happily helps me out.

• 花粉症を予防するために、眼鏡やマスクをして花粉から目や鼻を守ることが重要です。
  In order to prevent hay fever, it's essential to wear glasses and a mask, and protect one's eyes and nose from pollen.

EDIT: Here's one example:

• 日本語の言葉の背景色を灰色にするために、二つのグレイヴ・アクセント（``）を使う:

Which was corrected to:

• 日本語の単語の背景色を灰色にするには、二つのバッククォート（``）を使う:

Answer 1

The crucial difference is the absence vs. presence of the topic marker は. Possibility of omitting ため or に is dependent on this, and does not change the meaning so much, if any.

• A (ため)には is used for conditionals. It does not necessarily mean that A actually happened, but it means that whatever to follow is a necessary condition for A to happen. (There may be alternative ways to do it, but provided that context, that is the only salient way.) "in hope that A may happen, ...".

仕事で成功する (ため)には 、家で、喜んで私を助けてくれる夫が必要なのです。
'If I were to succeed in my business career, I would need a husband at home who would be happy to help me.'　(subjunctive)

花粉症を予防する (ため)には、眼鏡やマスクをして花粉から目や鼻を守ることが重要です。
'If you wanted to prevent hay fever, it is important to protect your eyes and nose from pollen by wearing glasses and a mask.

日本語の単語の背景色を灰色にする (ため)には、二つのバッククォート（``）を使う。
'If you wanted to change the background color of a Japanese word to gray, use two back quotes.

• A ため(に) is used when you are sure that A will actually happen, or A already happened.

仕事で成功する ため(に)、家で、喜んで私を助けてくれる夫が必要なのです。
'I need a husband at home who would be happy to help me so that I can continue being successful in my business career.'　　(indicative)

花粉症を予防する ため(に)、眼鏡やマスクをして花粉から目や鼻を守ることが重要です。
'It is important to protect your eyes and nose from pollen by wearing glasses and a mask in order to prevent (the on going) hay fever.

日本語の単語の背景色を灰色にする ため(に)、二つのバッククォート（``）を使う。
'In order to change the background color of a Japanese word to gray (right now), use two back quotes.

Answer 2

You are right in that when translated to English, they both become “in order to,” but they have different meanings.

AするにはB means “If I/you/someone wants to do A, then B.” AするためにB means “B, and it is in order to do A.”

Sometimes the distinction between these two are not important. If it has been already established that A is desirable, then both constructs can be used without changing the meaning much. I think that the first two sentences in your question are such cases. However, it is not always the case. For example, consider a sentence “Press the red button to launch a missile.” This English sentence can potentially mean two very different things:

• ミサイルを発射するには赤いボタンを押してください。 Press the red button if you want to launch a missile.
• ミサイルを発射するために赤いボタンを押してください。 Press the red button; it is in order to launch a missile.

Answer 3

ため can be tricky, since it can indicate both a cause-effect relation and a (let's call it) method-purpose relation.

When used for method-purpose, ために（は） is used after the purpose. Other replies have explained this thoroughly.

When used for cause-effect, usually ため (without the に) is used after the cause. This might seem counter-intuitive, since the cause can seem more similar to the method than the purpose:

雨が降ったため、試合が延期された
Since it rained, the game was postponed (not the game was postponed in order for it to rain)

Even more confusingly, even for cause-effect, ために (with the に) is sometimes used after the cause

雨のために試合が延期された
The game was postponed due to rain

I think this is mostly used after noun phrases (i.e. in the form のために), and when the cause-effect relation is evident.

Answer 4

It does not really fit with your examples but in my opinion,

AをするにB ⇒ objective. That you have to go by B to do A is a fact. Not an opinion, not a goal, it is like that.

AをするためにB ⇒ subjective. Here, that you have to go by B to do A is not a natural truth. It sounds more like an advice, an opinion etc...

Maybe it could help to show us which of your sentences have been corrected.