Editing Conjunction fallacy (section)

=== Tversky & Kahneman (1981)  ===

The original report by Tversky & Kahneman<ref name="tk81"/> (later republished as a book chapter<ref name="Tversky & Kahneman 1982"/>) described four problems that elicited the conjunction fallacy, including the Linda problem. There was also a similar problem about a man named Bill (a good fit for the stereotype of an accountant — "intelligent, but unimaginative, compulsive, and generally lifeless" — but not a good fit for the stereotype of a jazz player), and two problems where participants were asked to make predictions for events that could occur in 1981.

Policy experts were asked to rate the probability that the [[Soviet Union]] would invade [[Poland]], and the [[United States]] would break off [[diplomatic relations]], all in the following year. They rated it on average as having a 4% probability of occurring. Another group of experts was asked to rate the probability simply that the United States would break off relations with the Soviet Union in the following year. They gave it an average probability of only 1%.

In an experiment conducted in 1980, respondents were asked the following:

<blockquote>Suppose [[Björn Borg]] reaches the [[The Championships, Wimbledon|Wimbledon]] finals in 1981. Please rank order the following outcomes from most to least likely.
* Borg will win the match
* Borg will lose the first set
* Borg will lose the first set but win the match
* Borg will win the first set but lose the match</blockquote>

On average, participants rated "Borg will lose the first set but win the match" more likely than "Borg will lose the first set". However, winning the match is only one of several potential eventual outcomes after having lost the first set. The first and the second outcome are thus more likely (as they only contain one condition) than the third and fourth outcome (which depend on two conditions).