Conjunction Fallacy
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Conjunction Fallacy
Conjunction Fallacy is a cognitive bias that occurs when people overestimate the likelihood of two events occurring together, rather than one of the events occurring alone. This fallacy is often seen in decision-making and problem-solving contexts, where people may rely on heuristics or mental shortcuts to make judgments. The fallacy is related to the law of total probability, which states that the probability of an event occurring is equal to the sum of the probabilities of all possible outcomes. One reason why people may commit the Conjunction Fallacy is that they rely on representativeness, which is the tendency to judge the likelihood of an event based on how well it matches a particular prototype or stereotype. For example, if someone is described as being a feminist and a bank teller, people may judge it more likely that they are a feminist bank teller, rather than just a bank teller. This is because the conjunction of two specific attributes creates a more vivid and memorable mental image, which can lead people to overestimate its likelihood. Another reason why people may commit the Conjunction Fallacy is that they fail to consider the base rate, which is the overall frequency of an event in a given population. For example, if someone is asked to judge the likelihood of a person being a lawyer and a jazz musician, they may overestimate the likelihood of this conjunction because they are not considering the low base rate of jazz musicians in the general population. Overall, the Conjunction Fallacy is a common cognitive bias that can lead people to make erroneous judgments and decisions. By being aware of this fallacy and considering the base rate and representativeness heuristic, people can make more accurate judgments and avoid this bias.
cognitive bias, decision-making, probability, representativeness, base rate
Conjunction Fallacy
Conjunction Fallacy is a cognitive bias that leads people to overestimate the probability of two events happening together. It is based on how people think about two or more events happening together, even when it is more likely that only one of the events will happen. For example, if you were asked which is more likely; a person being a teacher or a teacher who is also a pilot, people often believe that it is more likely that a person is both a teacher and a pilot than just a teacher. This is incorrect because it is more likely that a person is just a teacher and not a pilot.
Conjunction fallacy, cognitive bias, logical fallacy, probability.
CITATION : "Thomas Lee. 'Conjunction Fallacy.' Design+Encyclopedia. https://design-encyclopedia.com/define/conjunction-fallacy?E=214055 (Accessed on October 14, 2026)"
Conjunction Fallacy
Conjunction Fallacy is a cognitive bias which describes the tendency for people to assume that the probability of two events occurring together is greater than the probability of one of the events occurring alone. This fallacy is based on the assumption that the conjunction of two events is more likely to occur than one of the events occurring alone. This fallacy is related to the law of total probability and is often seen in the context of decision making and problem solving. It is also known as the fallacy of the conjunction, or the fallacy of the single cause.
Probability estimation, heuristics, decision making, logical fallacy, cognitive bias.
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