Fallacy Friday!

Today's Logical Fallacy is...Shifting the Burden of Proof!

(related to “appeal to ignorance”) This fallacy occurs when the burden of proof is placed on the wrong side of an argument. In a logical...

Friday, December 11, 2015

Today's Logical Fallacy is... Argument from Ignorance!

(Argumentum ex Silentio, Ad Ignoratiam, Appeal to Ignorance)

This fallacy occurs when individuals take the lack of information about a certain subject as proof of either its existence or nonexistence. Essentially, it’s the belief that something is true because we don’t know it isn’t true, or, conversely, the disbelief in something because we don’t know that it is true. It is often used to justify a position that lacks a certain amount of evidence: proponents of extrasensory perception argue that because we don’t know everything there is to know about the brain that the brain can then send signals; UFO believers often use this argument when they argue that the lack of knowledge about lights or objects in the sky are proof of the existence of UFOs.

When we don’t have an adequate explanation, it is rational to say that we just don’t know – not to jump to a conclusion one way or another. Our knowledge about the world continues to grow, and just because we currently lack an explanation doesn’t mean that there is none or that the explanation is supernatural, paranormal, or otherwise “unnatural.”

Our legal system is designed to protect us from this fallacy: “innocent until proven guilty.” We don’t assume guilt; we wait until we have evidence “beyond a reasonable doubt.” At the same time, however, if a suspect has no alibi for a crime or “pleads the fifth,” it is often assumed that they are guilty – not due to any evidence but due to the lack of evidence. Assuming their guilt in this case, then, is a logical fallacy.

Intelligent design is based on this fallacy; the argument is that “gaps” in scientific knowledge are proof of God and anything currently unexplained must be divine. Structures that have been proposed as “irreducibly complex” have, in fact, been rejected and usually provide good opportunities for scientists to earn accolades in discovering the processes behind their evolution.

This fallacy may be applied when discussing religious beliefs. While religious beliefs themselves often include the "unknown" and thus a degree of ignorance, this fallacy only truly occurs when the belief is based on ignorance, i.e. "Because we have no proof that God doesn't exist, that must mean that he does exist." An individual may have subjective experiences that lead them to believe in a particular religion; as long as these conclusions are not assumed to be universal and thus objective, then their conclusion may be true for themselves.


“Scientists are never going to be able to positively prove their theory that humans evolved from other creatures because we weren't there to see it! So, that proves the Genesis six-day creation account is literally true!”

“The vet can't find any reasonable explanation for why my dog died. See! See! That proves that my neighbor poisoned him! There’s no other logical explanation!”

“You can't prove I'm wrong, so I must be right.”

“We can safely conclude that there is intelligent life elsewhere in the galaxy, because thus far no one has been able to prove that there is not.”

“Science can tell us nothing about God, which proves God doesn't exist.”

“Science can tell us nothing about God, so you have no basis for denying that God exists.”

“Mr. Hixel has no alibi for the evening of January 15th. This proves that he was in fact in room 331 at the Smuggler's Pass Inn, murdering his ex-wife!”

“We haven’t proved that Big Foot doesn’t exist; that means that he does.”

You can’t prove that there isn’t a mirror universe of our own, so there must be one out there somewhere!

Joe McCarthy said he was presenting to the Senate cases in which it was clear that individuals had Communist connections. With one case, however, he said "I do not have much information on this except the general statement of the agency…that there is nothing in the files to disprove his Communist connections." His argument was that because there was no evidence against a Communist connection for a person, that person must be working with the Communists. Source: Richard H. Rovere, Senator Joe McCarthy (Methuen, 1960), pp. 106-107.

There is no evidence for the Loch Ness monster; therefore, the Loch Ness monster does not exist.

Since the class has no questions concerning the topics discussed in class, the class is ready for a test.

No one on the council objected to the idea that he proposed, so everyone must think it’s a great idea.

She didn't say that I couldn't borrow her car, so I figured it was just fine if I borrowed it for the weekend.

Since you cannot prove that ghosts do not exist, they must exist.

Since scientists cannot prove that global warming will occur, it probably won't.

Fred said that he is smarter than Jill, but he didn't prove it, so it must be false.

You live on Sunny Street. You have a gun. Nobody else on Sunny Street has a gun. There was a murder on Sunny Street last night. You were involved.

You live on Sunny Street. You have a gun. The person was knifed. You were not involved.

Since no one has been able to prove Iraq doesn’t have weapons of mass destruction, we can conclude that Iraq must have them.

The fact that no traces of Hitler's remains we're ever found has led some people to conclude that he must still be alive.

When CBS News anchor Dan Rather was challenged about the authenticity of documents that indicated that George W. Bush had not fulfilled his National Guard duty as an honorable man, Rather was accused of using forged documents to discredit the president. Rather couldn't prove the documents weren't forgeries, but that doesn't prove that they were.

Obama hasn't proved he was born in the United States. Therefore, he wasn't born in the United States. Furthermore, no evidence he or anyone else brings forth can prove he was born in the United States. (The latter claim might also be branded the appeal to the impossible demand. The argument both demands proof and announces that nothing will count as proof.)

Hundreds of years ago, scientists made the same claim against bacteria – “I don’t see it, so it must not exist.” After the microscope allowed us to see smaller objects, the existence of bacteria was finally proved. These early skeptics fell into the trap of appealing to their own ignorance – another type of fallacy.

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