A simple event description such as "The boy jumped" does not necessarily imply anything about the speaker's understanding of the cause of the event or of the volition of the agent. I can say "The boy jumped" and mean that he was caused to jump involuntarily (e.g. by a sudden noise), or that he jumped of his own volition for a specific purpose (e.g. to reach something), or that he jumped of his own volition but for no reason or cause I can see, etc. Are there languages that mark such differences with verbal morphology, in the way that some languages mark evidentiality (which seems like a similar type of category)?
I'm not asking about argument structure-changing operations like causative forms; I'm asking if there are languages that inflectionally contrast forms of the same verb, with the same argument structure, with morphs that might be glossed as e.g. "involuntary action", "purposive action", "unknown cause", etc.
