Anecdotal Evidence Fallacy

Figure 1. Anecdotal evidence is the lowest form of information.

The anecdotal evidence fallacy is when someone uses a personal experience or an isolated example instead of a sound argument or compelling evidence.

Anecdotes can be be made up, misconstrued or be a statistical outlier which is insignificant when further evidence is considered.

Example

Let's say a person is considering a new diet plan and comes across anecdotal evidence from a friend:

Friend: "I started a new diet where I only eat one type of fruit every day, and I've lost a significant amount of weight in just a week!"

Instead of seeking more comprehensive and scientifically validated information on the effectiveness of various diet plans, the person decides to follow the same fruit-only diet based solely on their friend's anecdotal evidence. It would be better for the person to attribute a lower weight to the anecdotal evidence provided (as per Figure 1) and move up a step to larger studies of the wider populace.

How to counter the Anecdotal Evidence Fallacy.

To get to the truth of any subject critical analysis techniques should be used to judge the authority of the information source.

References