Anecdotal Fallacy
An informal fallacy where personal experience or a singular example is used to support an argument or position instead of compelling evidence. People often gravitate towards using their own experiences or those of people around them as evidence in arguments. It's natural to do so as citing scientific evidence to craft a good argument takes effort and most of us are lazy thinkers and opt for the quicker and easier System's 1 thinking versus the required metacognition of System's 2 thinking [1].
In the marketplace, this fallacy is encountered regularly in the form of testimonials. Marketers learned long ago to harness the power of a testimonial in order to influence your view on their product or service. To a degree, this is perfectly reasonable as there are many products offered where the experience is subjective (e.g., dining, uber/lyft, a hotel stay, business reviews in general, etc.), but you start go get into trouble when the product can be rigorously tested and quantified through scientific inquiry (e.g., supplements, global warming, homeopathy, etc.). This is a very important distinction. If you conflate anecdotes from subjective experiences with products that can be scrutinized objectively, you have moved into the realm of spurious arguments.
Furthermore, cognitive biases and logical fallacies are two distinct concepts, but they are often found together distorting your objectivity when constructing arguments. In this instance, the primary cognitive bias of influence is the availability heuristic. Recalling your own experience or the experience of those close to you, biases your objectivity towards this evidence as it must be more important since it is easily recollected. In fact, the idea that there is most likely scientific evidence available on a topic doesn't enter most peoples' calculus when weighing the evidence.
Logical Form
A typical logical form for such an argument is either:
Y occurred once with X.
Therefore, Y will occur every time with X.
Or:
Person Y told me that he saw/heard X.
Therefore, X must be true.
Examples
The following abbreviations are used in the examples below:
PN = The Nth premise for N = 1,2,3,…. (e.g., P1 is the first premise, P2 is the second premise, etc.)
C = Conclusion
1) Beyond the common appearance of the false cause fallacy, the use of anecdotes is common practice in complimentary and alternative (CAM) health circles. Many of the products, therapies, etc. that are offered haven't been properly studied, so the only evidence that is available to demonstrate the benefits are either anecdotes or case studies. Both are the weakest forms of scientific evidence in the hierarchy and shouldn't be used as the sole forms of evidence when structuring an argument.
Homeopathy, commonly found in CAM, is pseudoscientific nonsense. It was originally conceived in the late 1700s by a German physician and the underlying premise for the practice is that “like cures like.” In other words, homeopaths believe that a substance that causes symptoms of a disease in a healthy individual can also cure those symptoms when you're sick. If that appears nonsensical, it's because it is. The idea that something can simultaneously be the cause of illness and the remedy is contradictory. Put in terms of logic, it violates the Law of Non-contradiction. Something cannot be simultaneously true and false at the same time.
Beyond this logically contradicting position of “like cures like,” homeopathic “medicine” or what they call “remedies” are made through a dilution process, which is nonsensical from a scientific viewpoint. In this process, a selected substance is repeatedly diluted until the final product is chemically indistinguishable. The diluting substance of choice is primarily water, which means that after the dilution process, you are essentially left with just a vial of water. Further, between each dilution, the remedy goes through a “succussion,” which is where the solution is repeatedly shaken in order to “dynamize” it. It is believed that the act of succussion causes the solution to “remember” the original substance. To date, there is no evidence to suggest that water can somehow remember substances that were previously suspended in it [2].
Consider the following argument:
P1: I recently got the flu and started taking the homeopathic remedy Oscillococcinum.
P2: I definitely noticed that my symptoms were not that severe and I recovered from being sick in just a couple days when I'm normally sick for a week.
C: Therefore, homeopathy works. You should definitely try it the next time you get sick with the flu or have a cold.
Explanation: Using a personal experience with the flu and Oscillococcinum to try and convince you that it works is an anecdotal fallacy. No scientific evidence has been provided here demonstrating efficacy beyond placebo because it doesn't exist. To date, the best available evidence attributes any effects experienced by taking a homeopathic remedy to the placebo effect [3].
2) Marketers love testimonials as they're a great way to promote a product by harnessing the power of social proof. It’s the reason why Yelp and other review sites exist, why we assume that establishments with long lines must be great, crowded restaurants will have delicious food, and that participating in the most recent viral online trend must be a good idea. It's no secret that we're social animals and have a strong desire to fit in with our group. Evolutionarily, these traits exist as they are acutely important for our survival.
Social proof is a psychological phenomenon where people assume that since others are doing something, that they should be too. In other words, people tend to copy the actions of others in order to emulate their behavior and fit in with their surrounding group. This phenomenon is especially pronounced in ambiguous situations where others are viewed as being more knowledgeable even though this may not necessarily be the case (i.e., the crowd doesn't always know what's best). In the realm of digital marketing, it means that people are more likely to subscribe to your newsletter, tweet your content, or share a link to your site if they see others have already done these things.
Despite what your parents told you, life really is one big popularity contest. The perennial saying “It’s not what you know, but who you know,” has echoed throughout the ages and still holds true today. Particularly with social media where your personal worth is directly related to your number of followers and the likes you can amass. At some point, we went through a phase transition in our online spaces where people stopped caring about being correct and have become predominantly fixated on what’s popular. Facts have been replaced with misinformation, clickbait, and other forms of content that drives rabid engagement. We should all find this deeply troubling.
Explanation: Testimonials are anecdotes. However, some testimonials are completely fair, while others are deceptive; context is important. For example, a testimonial regarding a tutoring session is completely reasonable, while you should be skeptical of a testimonial given for a new supplement. Why? An experience with a tutor is going to be more subjective than one’s experience with a supplement. The tutoring experience is highly dependent upon the person doing the tutoring, while the supplement can be rigorously tested for efficacy through scientific inquiry. Last, it’s important to stay vigilant for sham testimonials as this will severely impact credibility.
3) Consider the following argument in regards to the COVID-19 vaccine:
P1: I didn't get the vaccine and have contracted COVID twice now.
P2: Both times it felt just like a cold and I recovered quickly.
C: Therefore, you really don't need the vaccine.
Explanation: While it's unfortunate contracting COVID twice, it's fortuitous that both cases were relatively mild given the vaccination status. However, just because the experience was mild without vaccination, doesn't mean that this will always translate to the experience of others. People have unique physiologies and there are multifarious aspects to human health. This is why scientific inquiry is so important as it will reveal, on average, how people respond to a particular disease as well as any medical interventions that are available to treat it. By harnessing the power of statistics, a better systemic view can be derived from which an optimal plan of action can be formulated.
4) Consider the following discussion between two individuals who are trying to decide on a restaurant to dine at:
1: Where would you like to go for dinner this weekend?
2: Not sure exactly, but I'd like to do something fancy.
1: That sounds good to me! How about we try that new place Lugo's? Their menu looks good and it has a 4 on Google with about 50 reviews so far.
2: What about Airy downtown? They're not as new as Lugo's, but the cuisine is similar and they have a 4.3 on Google with hundreds of reviews. Plus, we've never been there before.
1: Ok, that sounds good!
Now, let's further analyze the argument that Person 2 is making to Person 1 for why they should dine at Airy instead of Lugo's. It's beneficial to first place it in standard form while remembering to be charitable:
P1: Airy has been around longer than Lugo's.
P2: Airy also has a higher Google rating than Lugo's. A 4.3 versus a 4.
P3: Airy has hundreds of Google reviews versus Lugo's 50.
C: Therefore, Airy is the better choice and we should dine there.
Explanation: For the purposes of this example, let's assume all of these premises are true, which begs the question how do anecdotes play a role in this argument? The answer lies in the reviews themselves. A review is an individual's opinion of an experience with a product or service, which is no different from what appeared in the previous argument. However, the two examples diverge on a number of interesting points:
There are instances where listening to anecdotes is reasonable and doesn't lead to fallacious reasoning. As mentioned earlier, dining experiences are subjective experiences. In other words, there isn't a rigorous scientific experiment that I can devise that will tell me if I'm going to like the food at a restaurant or not. People have different palates that will lead one person to love the food at one restaurant while another person walks away from the same restaurant not all that impressed.
Furthermore, a dining experience encompasses more than just how the food tastes for most people. There is restaurant décor, the dining atmosphere, the professionalism of the staff – particularly your server, etc. There are a myriad of factors that play into one's dining experience, which further complicates how you would structure an experiment of this nature. In theory, it could be done, but having a large number of people review an experience is a good indicator of how your experience will be too as we'll discuss in the next point.
This example contains a large number of anecdotes versus a singular anecdote. This is a crucial distinction as we're transitioning from just one person's opinion to harnessing the wisdom of the crowd (WOTC). This is essentially a concept from statistics known as the law of large numbers (LLN), but with peoples' opinions. The LLN states that the average of the results obtained from a large number of trials should approach the expected value as more trials are performed.
In this instance, we have the opinions of a large number of people who, while individually are not all that credible, become increasingly wise as more individuals contribute and their results are collated to produce an overall rating for the restaurant. The number of reviews was accentuated in this argument and the WOTC is why.
Conclusion
Anecdotes are everywhere since it’s one of the most common forms of information communicated between one another. If you find yourself confronted with an anecdote being used as evidence in everyday discourse, it is important to stop and charitably analyze the argument. If you find that the anecdote is being used as the sole form of evidence when better evidence is available, remember that it renders the argument bad and it should be rejected. Moreover, if you find yourself improperly using anecdotes within one of your own arguments, as an individual who ascribes to the ethos of Critical Thinking, you must replace it with a good argument.
References
[1] Kahneman, D. (2011). Thinking, Fast and Slow. Farrar, Straus and Giroux.
[3] The Power of the Placebo Effect. Harvard Health. Retrieved from https://www.health.harvard.edu.