Logical Fallacy 4: Argumentum Ad Ignorantiam

Argumentum Ad ignorantiam means the Argument from Ignorance. It basically states that a specific belief is true because we don't know that it isn't true. This logical fallacy can also be called the Negative Proof Argument, or Appeal to Ignorance.

This is Part 4 in a series about Logical Fallacies. We are going through one fallacy at a time. There are many types of fallacious arguments. I'm going to try to explain them with examples then find ways to help you refute those arguments when they occur. Please comment or email if there's a particular fallacy you want me to tackle, or if you have success with refuting an argument using a good technique you can share.

James stated it quite perfectly in the comments of our last fallacy lesson:
Atheist: “You cannot prove that God exists.”
Theist: “Oh yeah? Well, you cannot prove that God DOESN’T exist!”
Of course this brings up the rule: The burden of proof lies on the person making the positive claim. Basically, if you state that god exists, the burden of proof lies on you.

Edit: I found this video today. Here is Dr. Neil deGrasse Tyson explaining it:

Example: You: The Big Bang is so amazing. It all seems so lucky that life arose through chance and happenstance and evolution in the primordial goo.
Opponent: Too amazing. I can't see how such a thing could happen. Therefore god did it. That's the only explanation that gives me all the answers.

Example: We know so little about the human brain. We can't prove that ESP doesn't exist, therefore it is real.

Example: Those funny lights in the sky don't look like anything I can recognize as a plane or helicopter, therefore it's an alien spacecraft.

This logical fallacy is quite common, in my experience. Now, how do you refute it?
  • First, tell your opponent that he or she has committed a logical fallacy. I find that this is a good way to start, by stating the logical error.
  • Second, tell them the burden of proof lies on the person making the positive claim. Also, extraordinary claims require extraordinary evidence. So claiming something such as ESP, an invisible man in the sky or alien visitation all require real evidence that can be proven and replicated and follow all the rules of good scientific research. The scientific research and math has been done over and over and validated regarding the Big Bang. That's pretty much well established. And the way it works, too, for such things, is that they are still working on the Big Bang. That's real science for you. That's how it really works.
  • Third, I think I'd mention that science never gives up, never stops searching for answers and even more questions. Whereas creationism and believing in fairy tales just gives up at the first step, as soon as thinking is required.
For this lesson, I’m using 4 resources:


  1. Yeah, that must be it. I love it when I state things perfectly :)

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