Would/could/might have + past participle

Hi. When you use the verb form "would have + past participle," "could have + past participle" or "might have + past participle," do you think we could think of the sentence having one of those verb forms to have an if-clause, whether it is there or not?

Or do you think having one of those verb forms marks the attitude of the speaker not being sure to a varying degree, with the verb "would have + past participle possibly being more sure than the verb form "might have + past participle"? (Not sure what I wrote correctly reflect what I wanted to say, though.)