Trouble With Modal Verbs In Past Tense (Präteritum)
I want to say something like "I should have gone" but I don't know if I need to use the helping verb sein here: ,,Ich sollte gegangen" oder ,,Ich sollte gegangen sein"
Likewise with haben: ,,Ich sollte ihn gesehen" oder ,,ich sollte ihn gesehen haben"?
If you want to say:
"I should have gone to the doctor, but I didn't"
that is, you're speaking about a hypothetical rather than a fact, then you'll want to use the subjunctive (Konjunktiv II). With modal verbs, that works like this:
"I should have gone to the doctor [, but I didn't]."
Ich hätte zum Arzt gehen sollen [, aber das habe ich nicht getan].
Other examples to help you see the pattern:
"I should have known better."
Ich hätte es besser wissen sollen.
"We should never have done that."
Wir hätten das niemals tun sollen.
"I should have asked you first."
Ich hätte dich zuerst fragen sollen.
"I should have done this a long time ago"
Ich hätte das schon vor langer Zeit tun sollen
To expand on both menino.leo and RobertHans782160 answers: "should have done something" translates to two different things in German: "sollte etwas gemacht haben" and "hätte etwas machen sollen".
menino.leo already covered "hätte etwas machen sollen".
"sollte etwas gemacht haben" means that something was supposed to have happened and you are assuming that it did.
For example, compare "He should have bought flour yesterday. He can bake a cake today" (er sollte gestern Mehl gekauft haben) with "He should have bought flour yesterday. He can't bake a cake today" (er hätte gestern Mehl kaufen sollen).
In my experience, "hätte ... sollen" is nearly always what you'll need.
Yes! Ok perfect, this is exactly what I wanted. I literally asked and gave the example using this construction correctly but everyone when off in a different direction
"Ich sollte ihn gesehen" does not make any sense as you must have the past aspect indicator – in this case "haben/sein", which under no circumstances can be left out. The past participle itself will not do.
The path is as follows: Ich gehe → ich bin gegangen → ich soll(te) gegangen sein
Ich mache → ich habe (etwas) gemacht → ich sollte (etwas) gemacht haben
Remember about the word order in the dependent clause: Er sagte, dass er es gemacht haben sollte.
Thanks for that, menino says above that you have to use konjunktiv for this (if talking about a hypothetical), does this construction you gave only work for non-hypotheticals? "I should have done that first", looking back and it being a fact?
That's not Präteritum. That's Perfekt. Your problem has to do with the formation of Perfekt. Your examples use that cumbersome Konjunktiv mode - but that's not the core issue here. Won't explain the subjunctive mode here - you're doing alright in this department.
Perfekt is formed by combining a past participle (gesehen, gegangen) plus one of the auxilliary verbs haben or sein. Can't just leave that out. Haben is much more common than sein. Sein is only used for some verbs. These verbs are often verbs that describe a motion. Often these verbs don't have a meaningful passive variant. Exceptions to this general rule of thumb may apply. A few verbs may take both sein or haben (won't get into the which and why here). E.g. Laufen, schwimmen, fliegen are associated with sein, while sehen (which can be used in passive voice) needs haben.