Logical Fallacy of the Conjunction Effect / Conjunction Fallacy

Conjunction effect is one of the many smokescreens that are used to cover the fact that the reasoning is based on one of the three fallacies of Agrippa's trilemma. Whenever a logical fallacy is committed, the fallacy has its roots in Agrippa's trilemma. All human thought (without Divine revelation) is based on one of three unhappy possibilities. These three possibilities are infinite regress, circular reasoning, or axiomatic thinking. This problem is known as Agrippa's trilemma. Some have claimed that only logic and math can be known without Divine revelation; however, that is not true. There is no reason to trust either logic or math without Divine revelation. Science is also limited to the pragmatic because of the weakness on human reasoning, which is known as Agrippa's trilemma. This is a fallacy that superimposes another level of fallacy on top or one or more of the three fallacies of Agrippa's trilemma.

The logical fallacy of the conjunction effect / conjunction fallacy occurs when a person thinks that a more specific condition is more likely than a more general condition. The conjunction fallacy is similar to the disjunction fallacy except that the conjunction fallacy mistakes a super-set for one more alternative of equal standing while the disjunction fallacy mistakes a subset or member of the more general class for an alternative of equal standing with the class. For instance, when asked, "Which is more likely, that you will meet a man or that you will meet a man with dark hair?" the tendency is to choose the more narrowly defined class as the most likely. For some reason, people tend to choose the more restrictive definition as most likely, but the opposite is the case.

Example of the Logical Fallacy of the Conjunction Effect / Conjunction Fallacy

The study, conducted among 350 Americans adults and 420 Canadian college students, asked participants to decide if a fictional driver damaged a parked car and left the scene, then found a wallet and took the money, was the driver more likely to be a teacher, an atheist teacher, or a rapist teacher? The participants, who were from religious and nonreligious backgrounds, most often chose the atheist teacher.

This is a quote from the Internet that is around on many sites and blogs. Of course, all atheist teachers and rapist teachers would be part of the larger group that includes all teachers, so it would more likely be someone in the group called all teachers. However, people missed the fallacy and selected atheist teachers as most likely to be untrustworthy.