68 - UFO Reports & David Hume On Miracles

Former Trump official John Ratcliffe (National Intelligence Director) recently suggested that there would be reports from the government that suggest the presence of alien spacecraft on Earth. Some members of the public, in response to this, have come to believe in alien visitation less. When would it be rational to believe that unexplained observations are aliens, and what does Hume's work on miracles have to do with this?
Toby Napoletano, Michael Hughes