Actions involving believing agents

Events whose causal explanation requires essentially a reference to a believing agent where the belief is part of the causal chain are not natural events in the same way that earthquakes or supernovas are natural events.

The key element here is that there is an essential causal role for human belief and action. Once these are introduced, the naturalness diminishes. Will it even be possible to divide the world up into two categories, natural events and human-caused events?