causer subjects

A causer is either an animate being who acts without volition or an inanimate entity.

If Rob tripped Roy just to see Roy fall, Rob is an agent, but if Rob tripped Roy accidentally, then Rob is a causer.

It is not always easy to tell whether an animate subject is an agent or a causer Out of context, we don't know whether the following subjects are acting deliberately or not.

Butch disgusts everyone. 
The child amused the adults.