Post hoc ergo propter hoc is Latin for "after this, therefore because of this." This Latin saying refers to a logical fallacy which we call the Post Hoc Fallacy. The Post Hoc Fallacy is expressed in this way: Event X transpires. Then, Event Y transpires. Thus, because X happened and Y happened right after, people associate causation between the two events (X caused Y). This pattern is especially dangerous when Event Y is an undesirable event. Whenever an undesirable event occurs, people look for the cause and try not to let it happen again. However, if Event X did not truly cause Event Y, then people will make the mistake of avoiding the repetition of Event X, which is not necessary. Thus, we have the Post Hoc Fallacy.
This logical fallacy can play out interestingly in the economic world. I would like to discuss a common application of this fallacy in the professional sports world. Let's say that the Philidelphia Eagles were to fire coach Doug Pederson this year and hire a new coach (Event X). Then, following their super bowl victory, say they had a 2-14 season (Event Y). Eagle's GM Howie Roseman would look back at the season and think, "What changed between this season and last season?" He would realize that a new coach was hired, and automatically blame it on the coach. However, was it possible that this victorious season was not the new coach's fault? Roseman would probably not think about that and may fire the new coach after his bad season.
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Another sports example of the post hoc fallacy is superstition. For example, maybe a Philadelphia Eagles fan wore a lucky jersey when watching the Eagles' super bowl win. There is no way that wearing the jersey had an impact on the game's outcome, but it's easy for people (especially die-hard fans) to believe that the game was won because of that lucky jersey.
ReplyDeleteCausation vs. correlation is another interesting connection to the post hoc fallacy. In economics, due to the complexity of businesses, the economy, etc., it is very difficult to determine what is the true cause of an event. In your example about the Eagles, while an outside observer might assume that the coach was responsible for the losing season, there is just as much chance that the coach had nothing to do with it, and there was in fact an alternative reason as to why the Eagles performed so poorly.
ReplyDeleteI like how you were able to apply the Post Hoc Fallacy to sports, since people don't usually associate economics with sports. I agree that people often attribute successes or failures of sports teams to a recent change to players or coaching, even though that is often not the cause. Similar to the superstitions, in track and field many athletes have very specific rituals that they will do while warming up, or right before their race. I know for me, that before I do my triple or long jump, I have to do the same two step before I start to sprint, or else I feel like my jump and rhythm is messed up, when I probably don't need to do it. Although my that step doesn't cause my jump to be good or not, because it is more correlation rather than causation.
ReplyDeleteIn addition to causation fallacies, such as the post hoc fallacy you explained your blog post, there is also a logical fallacy called the fallacy of composition. This fallacy is when someone assumes that something true for an individual or part is true for a group or whole. A sports related example is the idea that because when one person stands up during a sports game they have a better view, then when everyone stands at a sports game, everyone must have a better view. This is obviously false.
ReplyDeleteInteresting comparison of econ and sports,but it works well! I think its a universal thing to assume two events in close proximity are correlated; seems like its human nature to find a reason for everything.
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