If I were to say something like:
- "They couldn't have done X."
- "They're incapable of having done X."
- "It's not possible that they did X."
It can be interpreted in one of two ways:
- They're morally/psychologically incapable of doing X (like I'm physically capable of murdering someone, but I'd never be able to bring myself to do so).
- It's physically/logistically/biologically impossible for them to have done X (like it's impossible for the government to fake the existence of the Moon).
Is there any single word which will convey meaning #2, so I won't have to use some wordy phrasing like "they couldn't do it even if they wanted to"?