Some three decades ago, Edward De Bono related a story in his book on the Use of Lateral Thinking. The story went something like this –
“Many years ago when a person who owed money could be thrown into jail, a merchant in London had the misfortune to owe a huge sum to a money lender. The money lender, who was old and ugly, fancied the merchant’s beautiful teenage daughter. He proposed a bargain. He said he would cancel the merchant’s debt if he could have the girl instead.
Both the merchant and his daughter were horrified at the proposal. So the cunning money lender proposed that they let Providence decide the matter. He told them that he would put a black pebble and a white pebble into an empty moneybag and then the girl would have to pick out one of the pebbles. If she chose the black pebble she would become his wife and her father’s debt would be cancelled. If she chose the white pebble she would stay with her father and the debt would still be cancelled. But if she refused to pick out a pebble her father would be thrown into jail and she would starve.
Reluctantly the merchant agreed. They were standing on a pebble strewn path in the merchant’s garden as they talked and the moneylender stooped down to pick up the two pebbles. As he picked up the pebbles the girl, sharp eyed with fright, noticed that he picked up two black pebbles and put them into the moneybag. He then asked the girl to pick out the pebble that was to decide her fate and that of her father.
Imagine that you are standing on that path in the merchant’s garden. What would you have done if you had been the unfortunate girl? If you had had to advise her what would you have advised her to do?
What type of thinking would you use to solve the problem ? You may believe that careful logical analysis must solve the problem if there is a solution. This type of thinking is straight forward vertical thinking. The other type of thinking is lateral thinking.
Vertical thinkers are not usually of much help to a girl in this situation. The way they analyse it; there are three possibilities:
1. The girl should refuse to take a pebble.
2. The girl should show that there are two black pebbles in the bag and expose the money lender as a cheat.
3. The girl should take a black pebble and sacrifice herself in order to save her father from prison.
None of the suggestions is very helpful, for if the girl does not take a pebble her father goes to prison, and if she does take a pebble, then she has to marry the money lender.
The girl in the pebble story put her hand into the moneybag and drew out a pebble. Without looking at it she fumbled and let it fall to the path where it was immediately lost among all the others. ‘Oh, how clumsy of me,’ she said, ‘but never mind if you look into the bag you will be able to tell which pebble I took by the colour of the one that is left.’ Since the remaining pebble is of course black, it must be assumed that she has taken the white pebble, since the moneylender dare not admit his dishonesty.
The story shows the difference between vertical thinking and lateral thinking. Vertical thinkers are concerned with the fact that the girl has to take a pebble. Lateral thinkers become concerned with the pebble that is left behind. Vertical thinkers take the most reasonable view of a situation and then proceed logically and carefully to work it out. Lateral thinkers tend to explore all the different ways of looking at something, rather than accepting the most promising and proceeding from that.”