Derren Brown – The System

Last weekend, Derren Brown presented another of his occasional television specials. In this one he told us that he had invented a fool-proof system for predicting the winners of horse races. To demonstrate this system he introduced us to Khadisha who had received anonymous five winning tips from Derren. On the basis of these previous wins she borrowed £4,000 which she wanted to place on one final bit.

What Khadisha and the audience didn’t know was that there was no real system. Khadisha was one of 7,776 who Derren had initially contacted. All of those people had been given a tip for the first race. That first race had six runners and each of those horses was sent as the tip to 1,296 of those people. So 1,296 of them had a winning prediction and the other dropped out. This continued for four more races, with 5/6 of the group being eliminated at each stage. Over the course of five races this whittled the original 7,776 people down to one, Khadisha, who had received five winning tips. But because of the way the experiment was arranged, one of the original group had to have received five successful tips. Of course, at the beginning of the project, Derren had no way of knowing which of the original participants this would be.

So after five races, Khadisha is convinced that the system works. But that’s because she didn’t have the full picture. She only saw the system from her point of view. But that (flawed) perspective gave her enough confidence in the (completely fake) system to borrow a huge sum of money to bet on a horse race.

This was then used as the set-up for a magic trick where her horse loses, but Derren changes her betting slip to be a bet on the winning horse. To me, that’s not the interesting part of the programme. To me, the interesting thing is what this experiment shows about the nature of believe.

Going into the final race Khadisha had total confidence in the system. She had seen it working on the five previous races. She didn’t know how it worked (if you stop to think about it logically, there’s no possible way that it could have worked) but that didn’t matter to her. She just knew that it worked.

Of course, if she had seen the full picture there’s no way that she would have had the same amount of confidence in the system. If she had seen the full picture then she would have had no confidence in the at all. With all the information, she would never have borrowed that huge sum of money.

Derren hinted that this was a similar process to the one that convinces some people that homoeopathic remedies or alternative medicine works. A small number of people do see positive results following these treatments. But for a far larger number of people there’s no effect at all. But you rarely hear about the failures. If you went against you better judgement and tried a homoeopathic remedy that didn’t work, you probably wouldn’t shout about about it. You’d probably feel a bit embarrassed and want to keep it quiet. It’s the tiny number of people who feel better that you hear from. They are the ones who the homoeopaths shout about. They are the people who are only too happy to give you anecdotal evidence about how doctors could do nothing for their mother but how at the first sniff of primrose oil she was leaping around the room again.

Those people are like Khadisha. They don’t have the full story. Arguing from your personal experience has no relevance in cases like this. Something that works for you might not have worked at all for the majority of people. You might, like Khadisha, just be the random person who it will work for.

Derren Brown is very interested in this area. In his book Tricks of the Mind he has a great section on evidence and how people jump to conclusions when given incomplete evidence. I really recommend that you read it.