Chris is 35. He studied social philosophy and has had an interest in developing countries since he was a teenagers. After graduation, he worked for two years with the red cross in west Africa and then for three years in its Geneva head quarters, where he rose to head of the African aid department. He then completed an MBA, writing his thesis on corporate social responsibility. What is more likely? A Chris works for a major bank or B Chris work for a major bank where he runs its third world foundation. A or B?
Most people will opt for B. Unfortunately it is the wrong answer. Option B does not only say the Chris works for a major bank, but also that any additional condition has been met. Employees who work specifically within a bank third world foundation comprise a tiny subset of bankers. Therefore option A is much more likely. The conjunction fallacy is at play when such a sub set seems larger than the entire set - which by definition cannot be the case. Nobel Laureate Daniel Kahneman and Amostversky has studied this extensively. We are easy prey for the conjunction fallacy because we have an inate attraction to " harmonious"or " Plausible" stories. The more convincingly impressively or vividly Chris the aid worker is portrait, the greater the risk of false reasoning. If I had put it a different way you would have recognised the extra details as overly specific: for example ' Chris is 35 what is more likely? A Chris works for a bank he 24th or B Chris for a bank in New YOrk, where his office is on the 24th floor overlooking the central park. "
Here is another example: what is more likely? A Seattle airport is closed. Flights are cancelled. B Seattle airport is closed due to bad weather. Flights are cancelled. A or B? This time you have it: A is more likely since B implies that an additional condition has been met, namely bad weather. It could be that a bomb threat, accident or strike closed the airport; however, when faced with a ' Plausible" story, we don't stop to consider such things. Now that you are aware with it try it out with friends. You will see that most pick B
Kahneman believes that two types of thinking exists. The first kind is intuitive, automatic and direct. The second is conscious, rational, slow, laborious and logical. Unfortunately intuitive thinking draws conclusions long before the conscious mind does. For example, I experienced this after the nine eleven attacks on the world trade centre. I wanted to take out travel insurance and came across a firm that offered special " terrorism cover". Although other policies protected against all possible incidents ( including terrorism), I automatically felt for the offer. The high point of the whole farce was that I was willing to pay even more for this enticing yet redundant add on.
In conclusion : forget about left brains and right brains. the difference between intuitive and conscious thinking is much more significant. with important decisions, remember that, at the intuitive level, we have a soft spot for plausible stories. Therefore, be on the look out for convenient details and happy endings. Remember: if an additional condition has to be met, no matter how plausible it sounds, it will become less, not more, likely.
