Two different patterns involving modal
verbs
muss/soll/kann (etc.) gewesen sein vs.
hätte sein müssen/sollen/können (etc.)
muss/soll/kann (etc.) gesagt haben vs.
hätte sagen müssen/sollen/können
(etc.)
Note the existence of these different
patterns and their completely
different functions. They are a source
of difficulty because English speakers
often use the same construction ‘would
have’/‘could have’/‘must have’ etc.
for two distinct purposes: ‘He could
have gone to Oxford’, for example,
could mean ‘I think it is possible
that he did’ or ‘There was the
possibility, but it didn’t happen’. In
German these two meanings are
expressed using two different
structures.
(a) The muss gewesen sein/muss gesagt
haben pattern expresses an assumption
or a deduction on the part of the
speaker about an event assumed to have
taken place in the past. The speaker
voices the possibility or the
probability that something really did
happen in a certain way. This pattern
basically follows this special use of
the future perfect for expressing
assumptions (e.g. wird gewesen
sein/wird gesagt haben), but uses a
modal verb instead of werden.
The structure is as follows: Modal
verb (usually in the present tense) +
past participle of the main verb (e.g.
gewesen, gesagt) + haben or sein
depending on the main verb.
Examples:
"Sie kann die Inhaberin des Hotels
gewesen sein."
She could have been the owner of the
hotel (I suppose). (= It is possible
that she was the owner of the hotel.)
"Sie muss das gleich am Anfang gesagt
haben."
She must have said that right at the
outset (I suppose). (= It must be
the case that she did so. That is what
I suppose/deduce/expect.)
"Er soll die Stelle bekommen haben."
He is believed to have got the
job./They say he got the job.
(b) The hätte sein müssen/hätte sagen
müssen pattern expresses an unrealized
possibility attaching to an event in
the past. The speaker is effectively
asserting or implying that a
particular eventuality did not happen.
The structure is as follows:
hätte/hättest/hätten/hättet +
infinitive of the main verb + infinitive
of the modal verb. Note that this
structure is actually the simpler of
the two, because it always uses a form
of hätte even when the main verb is
one that forms the perfect and
pluperfect tense with sein.
Examples:
"Sie hätte die Inhaberin des Hotels
sein können."
She could have been the owner of the
hotel (but it didn’t happen).
"Sie hätte das gleich am Anfang sagen
müssen."
She would have had to say that right
at the outset (but she didn’t).
"Er hätte die Stelle bekommen sollen."
He ought to have got the job (but he
didn’t).