We like definitive answers and the comfort blanket of reassuring certainty. So, when we’re faced with not knowing, we tend to either spend a great deal of effort trying to find out or our mind reverts to some kind of pre-existing bias. Even if we say that we don’t know, we tend to live with, or gravitate towards, certain assumptions. It’s this tendency that lies at the heart of many logical errors and a lot of prejudice in the real world.

It’s known as the appeal to ignorance. Let’s say you read a story about a suspected criminal with a suitably surly, over-lit mugshot: “Oliver, 28, has been arrested on two counts of grievous bodily harm.” The definition of “suspected” is that we do not know if they’re guilty or not. They’re stuck in a legal limbo that is often enough to ruin most people’s lives. And yet, in your mind, you will likely have concluded their innocence or guilt. Sometimes, this is just bias, but at other times, it’s the “appeal to ignorance” at play.

“Oh, they’ve got no alibi; they must be guilty,” we might say.

It’s a fallacy because if we genuinely don’t know something, then there’s no telling if it’s this or that. So, if someone says, “You can’t disprove that aliens exist, so they must!” or “Oh, they didn’t call me back, so I can’t have gotten the job,” then they’re guilty of an appeal to ignorance.

It’s all to do with the burden of proof. It’s generally agreed in philosophy that those who are making a positive assertion — those who say, “This thing exists” — are obliged to provide the proof for that thing. In the absence of proof, we should not multiply complexities. You are innocent until proven guilty. Yes, I cannot disprove invisible fairies in my garden, but neither can I disprove pixies, goblins, angels, Jinn, or inter-dimensional nanobots, either.

The mind abhors a vacuum, and so when we don’t have proof, we fall back on biases that are given to us by the complex swathe of our upbringing. You might think Oliver is guilty because he looks “the wrong sort.” You might think him innocent because he looks like your uncle.

When have you seen the “appeal of ignorance”?