Friday, May 6, 2011

Friday Fallacy: Argumentum ad ignorantiam

So, it’s been a little while since I posted a Friday Fallacy.  I’ve been focusing on the job search.  Then, we had the wonderful week of storms and flooding.  The Kroger down the road flooded. Luckily, the liquor store next to it is on a hill and they sandbagged.  J  Kroger was nice enough to donate the food from the store, so it should have helped some of the displaced. 

So, this week’s fallacy is a fun one.  The argument from ignorance is pretty much what it says.  People will try to argue the validity of something because it hasn’t been disproven.  So, let’s say that I tell you the reason vacuums get that icky odor when they break is because of a microscopic vacuum skunk living inside the vacuum engine.  You argue that’s not the case, but don’t really understand the exact mechanical cause creating the icky odor.  Since you can’t tell me the mechanical details and since you can’t disprove the existence of the microscopic vacuum skunk, I declare victory in the debate.  The microscopic vacuum skunk causes the icky odor and, since you couldn’t give me an immediate alternative or disprove the mvs, I’m convinced you’re wrong.  It’s aggravating, and it’s also an argument from ignorance. 

It’s like when people argue for the existence of an afterlife.  There’s absolutely zero proof of life after death.  There’s also nothing conclusively disproving life after death either.  The appropriate state of mind is to not accept something until there is at least some evidence, but many people believe in a life after death (Heaven, Hell, Summerland, Valhalla, reincarnation, etc.).  These people will sometimes argue that they could be right by using the argument from ignorance.  Because no one has yet to disprove life after death, they argue that they must be correct in assuming reincarnation or heaven, or hell, or whatever. 

Just because we don’t know something for sure, doesn’t mean you can just pull something out of your nether regions and claim it’s factual.  You need verifiable proof.

There is one important note I should mention.  I think the “Logical Fallacies and Art of Debate” website says it best:

Whether or not an argumentum ad ignorantiam is really fallacious depends crucially upon the burden of proof. In an American courtroom, where the burden of proof rests with the prosecution, it would be fallacious for the prosecution to argue, "The defendant has no alibi, therefore he must have committed the crime." But it would be perfectly valid for the defense to argue, "The prosecution has not proven the defendant committed the crime, therefore you should declare him not guilty." Both statements have the form of an argumentum ad ignorantiam; the difference is the burden of proof.

In debate, the proposing team in a debate round is usually (but not always) assumed to have the burden of proof, which means that if the team fails to prove the proposition to the satisfaction of the judge, the opposition wins. In a sense, the opposition team's case is assumed true until proven false.

There are a zillion other example of this fallacy and several varieties of it.  Feel free to post some examples in the comments if you feel so inclined.

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