"trotzdem er es beispielsweise längst nötig gehabt hätte, das Hemd zu wechseln" from Der Verschollene by Kafka

Question

This post relates to nötig gehabt hätte as found in this passage from Der Verschollene by Franz Kafka.

›Einen besseren Rat kann ich ihm nicht geben‹, sagte sich Karl. Und er fand überhaupt, daß er lieber seinen Koffer hätte holen sollen, statt hier Ratschläge zu geben, die doch nur für dumm gehalten wurden. Als ihm der Vater den Koffer für immer übergeben hatte, hatte er im Scherz gefragt: »Wie lange wirst du ihn haben?« und jetzt war dieser treue Koffer vielleicht schon im Ernst verloren. Der einzige Trost war noch, daß der Vater von seiner jetzigen Lage kaum erfahren konnte, selbst wenn er nachforschen sollte. Nur daß er bis New York mitgekommen war, konnte die Schiffsgesellschaft gerade noch sagen. Leid tat es aber Karl, daß er die Sachen im Koffer noch kaum verwendet hatte, trotzdem er es beispielsweise längst nötig gehabt hätte, das Hemd zu wechseln. Da hatte er also am unrichtigen Ort gespart; jetzt, wo er es gerade am Beginn seiner Laufbahn nötig haben würde, rein gekleidet aufzutreten, würde er im schmutzigen Hemd erscheinen müssen.

I understand that, in this passage, Karl did have the need to change his shirt, but did not act on that need (i.e. kept on the same shirt).

QUESTION

1. How would one say that the need could have arisen, but did not. In concrete terms, the question would be how one could say in German something like:

   He was not grateful to his mother, who had paid a fortune to put him in first class, not in steerage as he deserved, even though otherwise he would have had the need to change his shirt a long time since.

   Here we are assuming that Karl didn't even have the need to change the shirt because it was so clean in first class.

   Another example might be a waiter's spilling something on your pants but not the shirt. Someone might say:

   Had the glass been full, you would have had to change your shirt.

2. I believe this question could be generalize to things like hätte können, hätte wollen, and hätte müssen, which all mean (if I am right) that someone could have, would have, should have, but didn't. (The ability, volition, or obligation came, but the person did not act on it.)

   For example,

   Er hätte es tun können.

   means

   He could have done it (but didn't).

   But sometimes you might want to say that an ability would have come to someone had things been different (but in reality that ability did not come). How do you say that in German?

   In concrete terms, the question would be how to say the following in German:

   (a) He would have been able to do it (but in fact was not able).
   (b) He would have been willing to do it (but in fact was not willing).
   (c) He would have had to do it (but in fact did not have to).

Answer 1

He was not grateful to his mother, who had paid a fortune to put him in first class, not in steerage as he deserved, even though otherwise he would have had the need to change his shirt a long time since.

Er war nicht seiner Mutter dankbar, die ein Vermögen aufgewendet hatte, um ihm einen Platz in der ersten Klasse zu verschaffen, nicht in der Holzklasse, wie er es verdiente, obwohl er dann andererseits sein Hemd schon seit langem hätte wechseln müssen.

The above sentence gives a reason so it's easy to know the meaning of the counterfactual thoughts. Let's forget about it and use a much simpler example:

Er hätte es wechseln müssen.

We can interpret this sentence in two ways:

• He had to change it if something happened. It didn't happen. No problem here.

• Something happened. He had to change it, but didn't. Now we can see the mess.

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Had the glass been full, you would have had to change your shirt.

Wäre das Glas voll gewesen, hättest du dein Hemd wechseln müssen.

The first clause introduces a counterfact. So the spilling is counterfactual and the change of the shirt is, too. Both did not happen. But let's spin it the other way:

Weil die Oma da war, hättest du dein Hemd wechseln müssen.

The first clause introduces a fact. Granny was there. Obviously, the counterfactual part is all about the change of the shirt. It did not happen.

The conclusion is, Konjunktiv is agnostic about the semantics. In contrary, the semantics depend on what's marked as factual and what's marked as counterfactual.

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Er hätte es tun können.

Again, Konjunktiv only tells this clause is counterfactual.

But sometimes you might want to say that an ability would have come to someone had things been different (but in reality that ability did not come). How do you say that in German?

Hätte er den Koffer da gehabt, hätte er das Hemd wechseln können.

Both clauses are counterfactual.

Weil der Koffer nicht da war, hätte er das Hemd eh nicht wechseln können.

Only the latter clause is counterfactual.

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EDIT: After the question was amended:

He would have been able to do it (but in fact was not able).

Er hätte es tun können.

He would have been willing to do it (but in fact was not willing).

Er wäre dazu bereit gewesen.

He would have had to do it (but in fact did not have to).

Er hätte es tun müssen.

Answer 2

As far as I understand the problem, it has nothing to do with the past. The ambiguity is there in the present as well.

In counterfactual conditionals, German and English seem to agree. (This yields the reading you paraphrased by "the obligation does not arise".)

Ich müßte abnehmen, wenn ich Jockey werden wollte.
I would have to lose weight if I wanted to become a jockey.

I hätte abnehmen müssen, wenn ich Jockey hätte werden wollen.
I would have had to lose weight if I had wanted to become a jockey.

However, German uses the Konjunktiv II of müssen for another purpose, namely to say that it would be a good idea to do something. English uses should in this case. (This yields the reading you paraphrased by "the obligation arises".)

Ich müßte/sollte abnehmen, aber es gelingt mir einfach nicht.
I should lose weight but I just can't.

I hätte abnehmen müssen/sollen, aber es ist mir einfach nicht gelungen.
I should have lost weight but I just couldn't.

I think the ambiguity you detect is between these two readings.

(good idea)
I should have changed the shirt but I didn't.
Ich hätte das Hemd wechseln müssen/sollen, aber ich habe es nicht getan.

(counterfactual)
I would have had to change the shirt if it hadn't been for the napkin.
Ich hätte das Hemd wechseln müssen, wenn die Serviette nicht gewesen wäre.

The same goes for können.

(counterfactual)
Wenn ich Ahnung von Mathe hätte, könnte ich dir vielleicht helfen.
If I knew anything about math, I might be able to help you.

(suggestion)
Ich könnte dir helfen. Wenn du willst.
I could help you. If you want to.

For wollen, the examples using Konjunktiv II sound funny because past indicative and past subjunctive are identical. So let's do these in the Perfekt.

(counterfactual)
Wenn du netter gefragt hättest, hätte ich vielleicht wollen.
If you had asked nicer, I might have wanted to.

(repressed wish)
Ich hätte schon noch bleiben wollen, aber du hast so gedrängelt.
I did want to stay, but you were in such a hurry.

Note that for müssen and können, Konjunktiv II can be replaced by würde plus infinitive only in counterfactual conditionals.

Looking at what you said in your second question:

But sometimes you might want to say that an ability would have come to someone had things been different (but in reality that ability did not come).

This is exactly what a counterfactual conditional is for. So hätten können, wollen, müssen fit. Note that counterfactual conditionals can be "hidden".

Fast hätte ich am Wochenende arbeiten müssen. Gott sei Dank ist der Kollege wieder rechtzeitig fit geworden.
→ Wenn der Kollege nicht wieder rechtzeitig fit geworden wäre…