might have done this and might have done that

[navi]

Which are correct:

1-He might be tall and he might not be tall.
2-He might be tall or he might not be tall.

3-He might be tall and he might be short.
4-He might be tall or he might be short.

5-He might have committed a crime and he might have saved people's lives.
6-He might have committed a crime or he might have saved people's lives.


I think '1' and '2' both work.
I don't think '3' really works.

To me '5' and '6' have different meanings. '6' means it is one of two things: either this or that.
'5' seems to be saying that the two things are independent and not necessarily mutually exclusive. It might even be possible that he might have saved lives by committing a crime. That would probably best be expressed by:

7-He might have committed a crime and saved lives.

Gratefully,
Navi.

[Bobinwales]

1-He might be tall and he might not be tall. The only use I can think of is a girl teasing her friend about the boyfriend that she hasn't introduced her to yet.
2-He might be tall or he might not be tall. Similar, but not as effective.

3-He might be tall and he might be short. The answer to, "What sort of man are you looking for?".
4-He might be tall or he might be short. Similar

5-He might have committed a crime and he might have saved people's lives. He might have committed a crime but he might have saved people's lives
6-He might have committed a crime or he might have saved people's lives. I cannot see a use for the phrase.

7-He might have committed a crime and saved lives. The two elements are not connected.

Please remember that I am not an expert, just a native speaker. The other Wizards may well disagree with me.

[Erik_Kowal]

If you say you are a native speaker, Bob, I would be very presumptuous to dispute it.

[Bobinwales]

See what I mean about not being an expert?

I should have said, "The other Wizards may disagree with my thinking"!

[Phil White]

I can think of contexts where any of these would be fine, but it is only the context that determines the appropriateness.

To take just one that Bob had problems with:
6-He might have committed a crime or he might have saved people's lives.
Think of a conflict scenario (exactly this scenario is described in the film "Apocalypse Now"). A commander in a war sees that the enemy always seems to know what his own troops intend to do, and his unit is suffering high casualties. He suspects spies and has two local aides summarily executed. The number of casualties suddenly falls:
"He might have committed a crime or he might have saved people's lives. Whatever you think, he found the right people."

Underlying all your questions is the issue of the distinction between "and" and "or". It is more complex than most people imagine. I was recently working on a translation and found that I was regularly translating the German word "und" (and) with "or". Either "and" or "or" would have been okay in the German or the English, but I regularly preferred "or". The reason is that the basic meanings of the words actually overlap in some contexts.

As Bob pointed out, your sentences 1 and 2 have the same meaning. Since he cannot simultaneously be tall and not tall, the normal meaning of "and" makes no sense. The "and" is simply being used to join the two statements together. In writing, you could use a comma or a semicolon to achieve the same effect. I cannot really see that "or" in the same sentence is serving any other purpose either.

The same applies to sentences 3 and 4. Again, this is because he cannot be simultaneously tall and short.

With sentences 5 and 6, it is possible to use the same argument, in other words, there is no significant difference between the sentences. However, it is possible for both statements to be true simultaneously, and therefore different readings that depend on the different meanings of "and" and "or" are possible. Your comments indicate that you are fully aware of this.

Exactly how to read the sentences depends entirely on further context.