Lesson 35: Appeal to Ignorance

Spot the Faulty Logic #

“No one has ever proven that aliens DON’T visit Earth. So aliens must visit Earth!”

Discussion: Talk with your teacher about this example. Is lack of disproof the same as proof?

How/Why It’s Often Used #

This fallacy exploits the gaps in our knowledge. When we don’t know something for certain, there’s temptation to fill that gap with whatever belief we prefer. The reasoning goes: “Since we don’t know for sure, my belief is as good as any.”

It’s closely related to the Burden of Proof fallacy, but focuses specifically on using lack of knowledge as positive evidence. It appears in discussions about the paranormal, conspiracy theories, and claims that are hard to test directly.

Appeal to Ignorance in Action #

Did you spot the faulty logic? #

The fact that we haven’t disproven alien visits doesn’t prove they happen. The correct conclusion from lack of evidence is “we don’t know,” not “therefore it’s true.” We need positive evidence for a claim, not just absence of disproof.

Second Example #

“Scientists haven’t proven that this supplement works. So it must not work.”

The Flaw #

Lack of proof isn’t proof of absence. Maybe the supplement hasn’t been studied yet. The honest conclusion is “we don’t know if it works” - not “it definitely doesn’t work.” More research is needed.