Exposing PseudoAstronomy

December 9, 2009

Logical Fallacies: Argument from Ignorance (or, Ad ignorantiam)


In my ever-increasing series on logical fallacies, this post is going to discuss a rather large class of fallacies, underwhich the God of the Gaps fallacy falls — Argument from Ignorance.

What is the “Argument from Ignorance” Fallacy?

The Latin term for the fallacy is ad ignorantiam. The Argument from Ignorance is – yet again – a fallacy that is aptly named: It is an argument that is made from pure ignorance about a subject purely because of that ignorance. The basic structure of the argument is that there is an observation, that observation is unexplained (ignorance), and so someone will insert their own explanation with certitude.

Example from UFOlogy

Okay, first I have to make this side-comment: I write these posts in a separate text editor because I don’t like how little WordPress displays on the screen. I use Apple’s “Text Edit” program which automatically underlines words that are misspelled. Apparently, UFOs = aliens is so popular in our culture that “UFOlogy” is considered a real word in Apple’s built-in dictionary. Sigh.

Anyway … in the realm of pseudoastronomy (which Apple’s dictionary says is not a real word), UFOlogy folks are some of the biggest users of the Argument from Ignorance (unless you consider the sub-type of God of the Gaps, in which case it’s the young-Earth creationists). Most UFOlogists will generally follow the following “logic:” (1) Someone sees something in the sky. (2) They cannot explain what it is. (3) They make a report of it and their friendly neighborhood UFOlogist sees it. (4) If they pursue it, they will generally say that it is very likely to be an alien craft. This is despite any actual evidence of, well, anything other than an “eyewitness report” of something that that eyewitness could not explain.

This is a classic example of the Argument from Ignorance because they have taken an unknown (the UFO) and without any evidence have stated that it is likely to be an alien craft.

It is just as likely that they are demons (I have heard a Catholic monk claim this).

Or it is just as likely that they are the souls of people who have just died going up to the spirit world (I have also heard this claim made).

Or (now bear with me here …) it could much more easily be something they couldn’t identify, such as a satellite, a meteor, another celestial object, a white bird (I have 3 times seen what initially were UFOs making all sorts of weird moves only to watch a little longer as they headed towards a light source and were just a flock of white birds), a firefly, or something else.

Final Thoughts

The Argument from Ignorance has many sub-types, though really I think the God of the Gaps is the most often-used of the sub-types. It is pretty easy to spot as long as you pause after someone has made a claim and figure out if they have backed it up with anything. If not, then it could very well be an argument from ignorance.


  1. I need to see the T-Rex logical fallacy.

    http://www.qwantz.com/index.php?comic=1540 [Note from moderator – link is PG-rated.]

    Comment by Mike — December 15, 2009 @ 2:15 pm | Reply

  2. The argument ad ignorantiam has some specific features which i’m afraid you’ve missed. Its main problem is not that it relies on ‘unproven facts’ or ‘unknown proof’ or ‘lack of knowledge’. Consider this: if we meet on the street and I ask you for directions, you tell me where the Central Station is, and I believe you and follow the path you mentioned: did you argued from ignorance? Consider yet another example: if a doctor tells you that you need an operation – knowing that you have no skills in medicine whatsoever – did he argued from ignorance? When the government says that the stock market is low and measures x, y, and z should be adopted – knowing that few people know what x, y and z actually mean -, did they argued from ignorance?

    I suppose you figured the answer is ‘No’. The form of the ‘ad ignorantiam’ is: Ghosts exist because nobody has yet proven their non-existance. It is also called ‘shifting the burden of proof’. Which means that simple (as less probable as they’d be) claims based on ‘position-to-know’ testimony (the eyewitness) could not be seen as ad ignorantiam’s.

    Nice blog, anyway.

    Comment by ARGUMENTICS — December 23, 2009 @ 6:00 am | Reply

  3. Absence of evidence is not evidence of absence. Would it be OK if they said “it MAY have been an alien craft” or “ghosts MAY exist”. There is no evidence that they don’t is there?

    Comment by Steve — December 24, 2009 @ 5:26 am | Reply

  4. “Absence of evidence is not evidence of absence.”

    Depends. When do you abandon a search for a dinosaur in the Congo or Bigfoot in Washington state and conclude the absence of evidence means the safe money bet is on its non existence?

    Comment by kamamer — January 14, 2010 @ 12:01 pm | Reply

  5. This is true. It is the “beyond reasonable doubt” stance. But how long did they look for a black hole before they found one (and then a lot). Even Einstein “fiddled” his equations (added a constant) to prevent the prediction of the unlikely observation that the universe was expanding (the safe money bet). It was ‘unexpected’ that Hubble (the guy not the telescope) would show otherwise. I suspect that the ‘safe money bet’ in science is not a ‘safe money bet’. Best keep an open mind ay!

    Comment by Steve — January 15, 2010 @ 4:16 am | Reply

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