Series on Logical Fallacies – The Anecdotal Fallacy

Uncertainty and Misinformation

At Dear Pandemic, we want to dish out science facts AND equip our readers with tools to make sense of data and science themselves.

This is post is part of an ongoing series by Dr. Kristen Panthagani of You Can Know Things, in which she dissects common logical fallacies that have led people astray during the pandemic.

⚠️The Anecdotal Fallacy

The anecdotal fallacy occurs when people use their limited personal experience to make sweeping conclusions about a given topic. It is an exceedingly common fallacy to commit, and nearly everyone has done it at one point or another. We are used to making conclusions based on our personal experiences because in many areas of life, anecdotal evidence (evidence from personal experience) is the only kind of evidence we have. However, when it comes to things like vaccine side effects, personal experience alone is not enough to decide if a symptom is caused by a recent vaccination or something else.

Imagine a person had scheduled to get a COVID vaccine on Monday, but then had to cancel last minute. Now imagine later that day, they happened to have a thoroughly obnoxious twitch in their hand. If they had gotten vaccinated, they may have been tempted to conclude the vaccine caused the twitch, even though it was going to happen anyways and would have been coincidence. When millions of people are getting vaccinated, coincidences like these are statistically bound to happen. However, some symptoms are truly caused by vaccines. The anecdotal fallacy assumes that personal experience is enough to know when it’s coincidence and when it’s not. This isn’t true: in order to truly know which symptoms are caused by vaccines, it needs to be studied systematically across large groups of people, not deduced from limited stories.

A note on logical fallacies:

Logical fallacies are common patterns of reasoning that seem true on the surface but have one or more critical flaws. At their root, many are oversimplifications–like a cognitive shortcut. They are appealing because they make something complex, like vaccine safety or the efficacy of masks, into something simple and easy to understand. However, this oversimplification often leaves out important details, leading to the wrong conclusions.

Logical fallacies are common and used by people arguing both for and against nearly every pandemic topic. They are NOT a sign of stupidity or lack of intelligence: they have tripped up nearly everyone at some point. And just because someone uses a fallacy in their argument doesn’t automatically mean they’re wrong — (that’s the fallacy fallacy!). It simply means they haven’t provided adequate evidence supporting their argument, but that evidence may in fact exist. It’s useful to recognize logical fallacies in our own thinking so we can make more accurate conclusions about the world around us.