Is there any rules for the ordering of modal verbs within a German sentence?

Question

I've recently come across the fact that when there are 2 modal verbs in a sentence, they seem to take the opposite order to English modal verbs (even apart from one being at the end of the sentence).

This is really critical to sentence comprehensibility but I can find no grammatical explanations on the subject.

Can someone please explain if there is a rule for this or why it's different to English?

Please see examples below:

In 10 Minuten können Sie das machen sollten - In 10 minutes you should be able to do that

My English brain wanted to say: "In 10 Minuten sollten Sie das machen können"

Er hätte das dürfen sollen - He should have been allowed to do it

Das hätte nicht passieren dürfen - That shouldnt have been allowed to happen

Answer 1

Klammern with parts belonging together put around something else is the most important pattern of German sentence structure. It's used everwhere, not just with modals. Of course, that means the order of the items at the end of the sentence is reversed.

Sie 'some action'

Sie 'hätte ‹some inner action› sollen'.

Sie 'hätte ‹heute «some innermost action» können› sollen'.

Sie 'hätte ‹heute «lesen» können› sollen'.

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Your examples:

In 10 Minuten sollten Sie das machen können.

In 10 minutes you should be able to do that.

This is in fact correct. While

In 10 Minuten können Sie das machen sollten.

is ungrammatical. However,

In 10 Minuten könnten Sie das machen sollen.

means

In 10 minutes you might be requested to do that.

Er hätte das dürfen sollen.

He should have been allowed to do it.

Again, correct.

Das hätte nicht passieren dürfen.

That shouldn't have been allowed to happen.

Again, correct.

Answer 2

Modal verbs are not different from any other kind of verb as far as order is concerned.

The order of verbs in German is almost the opposite of that in English. In fact, in subordinate clauses, it is the opposite:

that he needs₁ to rest₂
daß er sich ausruhen₂ muß₁

because they need₁ to be able₂ to communicate₃
weil sie kommunizieren₃ können₂ müssen₁

which your doctor should₁ be able₂ to detect₃
was dein Arzt erkennen₃ können₂ sollte₁

Of course, the finite verb sometimes has to be fronted:

Muß₁ er sich ausruhen₂?
Wer muss₁ kommunizieren₃ können₂?
Dein Arzt sollte₁ das erkennen₃ können₂.

There is actually one additional problem involved. English and German employ different strategies to get the "past hypothetical" meaning of modals.

English uses modal plus infinitive perfect:

You should not worry. – You should not have worried.
You could call me. – You could have called me.

German uses the the perfect of the modal, with the auxiliary in the past subjunctive (Konjunktiv II), plus infinitive.

Du solltest dir keine Sorgen machen. – Du hättest dir keine Sorgen machen sollen.
Du könntest mich anrufen. – Du hättest mich anrufen können.

The cause for this difference being that English modals are defective and don't have perfect forms, whereas German modals do.

Answer 3

First you need to understand the simple cases (one or two verbs) before trying to get to the more complicated ones.

If there is only one verb, its position depends on whether the sentence is a yes/no-question (verb first), a statement (verb second) or a subordinate clause (verb last [usually]):

(1) Erkennt er das? (Verb first)
(2) Er erkennt das. (Verb second)
(3) Ich weiß, dass er das erkennt. (Verb last)

When the verb consists there is a finite modal verb and an infinite verb, in the cases (1) and (2) we get a sentence bracket: The finite modal verb is first or second, and the infinite verb goes to the end of the sentence. In case (3) the finite modal verb is at the end of the sentence, and the infinite verb goes right before it:

(1) Muss er das erkennen?
(2) Er muss das erkennen.
(3) Ich weiß, dass er dass erkennen muss.

Now let's add a third infinite verb:

(1) Muss er das erkennen können?
(2) Er muss das erkennen können.
(3) Ich weiß, dass er das erkennen können muss.

Let's take a closer look at these sentences The logical dependency of the verbs is: müssen -> können -> erkennen. That's the order you use in an English sentence: He must be able to recognize this.

We can see that the first verb stays at its position (first for the question, second for the statement, last for the subordinate clause)

The second verb also keeps the same position the second verb would have if there where only two verbs: Last in cases (1) and (2) when there is a sentence bracket, second-last in case (3) when the (logically) first verb is last.

The (logically) third verb now is immediately before the second verb, in all three cases.