In the month of March, 1981, then-President Ronald Reagan was shot by noted cinephile John Hinckley. In April, Nancy Reagan hired astrologer Joan Quigley as a White House advisor and early gunshot warning system.

Nancy’s belief in the ability of the stars to predict and guide events lead to Quigley being kept on staff for the next seven years. There is no way of knowing the full extent of her involvement in the Reagans’ decision making. Numerous sources confirm that at the very least, her advice was regularly taken into account in the scheduling of flights, summits, and speeches.

Whether or not you believe that elemental furnaces burning light-years away can directly shape a human’s destiny here on Earth, we see them shape our destinies indirectly every day. A belief doesn’t have to be scientifically accurate to lead someone into action, and human action is unavoidably real. Through deluded intermediaries, any fiction can be turned into something measurable, present, and confronting.

No matter how they are made, predictions have a way of changing the events that follow. A widely used system for making predictions, whether it’s astrology, dowsing, or opinion polling, will eventually take on a life of its own as more and more people use it to guide their actions. Wars, migrations, successions, and assassinations have always hinged on the information that people think they have, and much as we would like to believe it, bad sources don’t always lead to failure.

When Joan’s position in the Reagan White House became public knowledge, Carl Sagan said, “Some portion of the decision-making that influences the future of our civilization is plainly in the hands of charlatans.” Whether she was the only charlatan on staff is another question, but there can be no doubt that her methods are what made the first lady feel secure and willing to listen. It’s hard to justify changing a president’s flight plan based on a feeling – even expertise is easier to doubt than the unchanging heavens, if you’re into that kind of thing already.

This is more than a history lesson. There’s a practical skill hidden in all of this. When you’re faced with someone who is wrong – someone who believes something you can prove isn’t true, who bases their decisions on false premises – don’t bother to contradict them. Instead, now you have information you can use to predict their actions – if you’re a charlatan yourself, you can even change what they do next.