Mason's explanation is basically that there's a flying saucer full of little green men, hovering just out of sight, who have the world enveloped in their thought controlling rays.

Now Mason is immune to these rays and is the only person left on earth who is capable of independent thought.

Unfortunately, because the rest of us are under the influence, nobody believes anything he says.

But of course, he's right and everyone else is wrong.

He's thinking of changing his name to Cassandra.