Lesson 25: Genetic Fallacy

Spot the Faulty Logic #

“You can’t trust that scientific theory - it was originally developed by someone who lived 200 years ago. What could they possibly know?”

Discussion: Talk with your teacher about this example. Does where an idea comes from determine if it’s true?

How/Why It’s Often Used #

We sometimes make shortcuts by judging ideas based on where they come from rather than examining them directly. If an idea comes from a source we like, we accept it. If it comes from a source we dislike or distrust, we reject it. This saves time but can lead us to wrong conclusions.

This fallacy works in both directions - rejecting good ideas because of their origin, or accepting bad ideas because they come from a favored source. It’s related to Ad Hominem, but focuses more broadly on origin rather than just the person arguing.

Genetic Fallacy in Action #

Did you spot the faulty logic? #

The age of a theory doesn’t determine its validity. Many scientific principles developed centuries ago are still accurate. What matters is whether the theory is supported by evidence and testing, not when or by whom it was first proposed.

Second Example #

“That peace agreement idea came from our rival country, so it must be a trick.”

The Flaw #

Even rivals can propose genuinely good ideas. The proposal should be evaluated on its actual terms - is it fair? Does it address the issues? - not dismissed simply because of who suggested it.