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Argument from Ignorance

ad ignorantiam

(also known as: appeal to ignorance)

Description: The assumption of a conclusion or fact based primarily on lack of evidence to the contrary.  Usually best described by, “absence of evidence is not evidence of absence.”

Logical Forms:

X is true because you cannot prove that X is false.

X is false because you cannot prove that X is true.

Example #1:

Although we have proven that the moon is not made of spare ribs, we have not proven that its core cannot be filled with them; therefore, the moon’s core is filled with spare ribs.

Explanation: There is an infinity of things we cannot prove -- the moon being filled with spare ribs is one of them.  Now you might expect that any “reasonable” person would know that the moon can’t be filled with spare ribs, but you would be expecting too much.  People make wild claims, and get away with them, simply on the fact that the converse cannot otherwise be proven.

Example #2:

To this very day (at the time of this writing), science has been unable to create life from non-life; therefore, life must be a result of divine intervention.

Explanation: Ignoring the false dilemma, the fact that we have not found a way to create life from non-life is not evidence that there is no way to create life from non-life, nor is it evidence that we will some day be able to; it is just evidence that we do not know how to do it.  Confusing ignorance with impossibility (or possibility) is fallacious.

Exception: The assumption of a conclusion or fact deduced from evidence of absence, is not considered a fallacy, but valid reasoning. 

Jimbo: Dude, did you spit your gum out in my drink?

Dick: No comment.

Jimbo: (after carefully pouring his drink down the sink looking for gum but finding none...)  Jackass!

Tip: Look at all your existing major beliefs and see if they are based more on the lack of evidence than evidence.  You might be surprised as to how many actually are.

References:

Walton, D. (2010). Arguments from Ignorance. Penn State Press.


Registered User Comments

Dan Waller
Thursday, July 04, 2019 - 12:06:44 AM
Surely Athiesm must be an argument from ignorance then. "There's no evidence for God. Therefore God does not exist"

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Bo Bennett, PhD
Thursday, July 04, 2019 - 06:06:11 AM
That's not atheism. What you presented is a bad argument someone might give for atheism, and yes, that would be fallacious reasoning. Atheism is the disbelief in any gods - there is no reason included in the definition. Those atheists who insist that no god can possibly exist (rather than just stating that they don't believe in any gods) need to provide evidence to support that claim.

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Dan Waller
Thursday, July 04, 2019 - 11:54:33 AM
@Bo Bennett, PhD: Yeah thanks for the correction. I realized Its not what I meant to say Athiesm is just one sentence as I understand it. Its just i've been thinking about it recently after a recent conversation with an athiest who presented that very argument. Then he tried to put the "burden of proof" onto me for believing in a God with no proof of a God. With this in mind my questions are as follows.

1)Surely the burden of proof can't be on me. In response to a fallacy?

2) I do not believe that in order to believe something you have to necessarily have conclusive proof for that thing. So with that in mind isnt that a fallacy in itself to even argue that point? I can't see how it would be a logical premise based on the fact that we believe lots of things without conclusive proof

3) Would it be logical to argue that it is possible to believe(rather than lack belief) something because of no proof. For example.

The Sun goes down every night
There is no proof the Sun will not go down tonight
Therefore the Sun will go down tonight

This would still be a fallacy correct? But would it be one from ignorance? Because its based on proof that the sun always goes down or at the very least evidence.

Sorry for all the questions. Im literally brand new to logic but I think its really interesting.

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Bo Bennett, PhD
Thursday, July 04, 2019 - 02:02:28 PM
@Dan Waller:

1) If you claim that a god exists, the burden of proof is on you to make your case. If you simply claim that you have found enough evidence to warrant belief in a god, they you should be able to share that evidence.

2) No reasonable person would as for "conclusive proof" when debating gods. Evidence is what matters, not mathematical or logical proof.

3) You are referring to a process called induction. It is reasonable to believe that the sun will rise tomorrow based on the history of it rising every day. Again, this is strong evidence. Evidence is what matters, not necessarily "proof".

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Nitonise
Thursday, June 20, 2019 - 12:47:05 PM
I think "absence of evidence is not evidence of absence" doesn't work if we think probabilistically rather than deductively (i.e. instead of being sure that X is absent we just become more sure about it). There is a good proof that absence of evidence IS evidence of absence, follow the link.

https://i.stack.imgur.com/TMMfc.png

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Bo Bennett, PhD
Thursday, June 20, 2019 - 12:56:09 PM
"Absence of evidence is not evidence of absence" generally works when we would not expect to find evidence.

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Nitonise
Thursday, June 20, 2019 - 01:13:43 PM
@Bo Bennett, PhD: I see what you mean, but I still don't see how you can make it fallacious for probabilistic reasoning. Could you possibly give me an example, so I could apply Bayes theorem and check out if absence of evidence is evidence of absence?

Alternatively you could try to refute the proof that I have given.

Or did you mean "generally works when we would not expect to find evidence." in context of deductive reasoning instead?

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Bo Bennett, PhD
Thursday, June 20, 2019 - 02:11:57 PM
@Nitonise: I think the wiki page on this says it better than I could: https://en.wikipedia.org/wiki/Evidence_of_absence .

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Nitonise
Friday, June 21, 2019 - 12:16:18 AM
@Bo Bennett, PhD: After thinking about it I think the answer is following: Yes, it can be the case that argument from ignorance can be valid. But not always, it's valid for situation that was described in the proof. In the proof we have absence of evidence that is at the same time the negative test result. We made successfull attempt to get test result (i.e. we successfully performed a test), but we didn't get the positive test result. In these circumstanses absence of the positive test result is the same thing as getting the negative test result.

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Sam Carver
Sunday, June 16, 2019 - 03:03:53 PM
In a quote from Jimmy Carter that has circulated on Facebook it states, "Homosexuality was well known in the ancient world, well before Christ was born and Jesus never said a word about homosexuality. In all of his teachings about multiple things -- he never said that gay people should be condemned. I personally think it is very fine for gay people to be married in civil ceremonies.“
The implication by Carter, which is the use to which the quote has been cited, is that Jesus must have approved of homosexuality. I find the implicated conclusion to be a fallacy of Argument by Ignorance. Would I be correct in referring to that implication as being of that particular logical fallacy? Thanks.

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Bo Bennett, PhD
Sunday, June 16, 2019 - 03:35:54 PM
Good question. I think we can make some fair assumptions here and put this in a syllogism:

1. Carter (a Christian) would not disagree with Jesus on a moral issue.
2. Carter is okay with civil gay marriage.
3. Therefore, Carter believes that Jesus would be okay with civil gay marriage.

Based on this, it would seem as if the argument from ignorance applies, but we cannot know if Carter used other information to come to that conclusion such as other Biblical references, the character of Jesus, etc. It is good practice to give others the benefit of the doubt before calling "fallacy." In this case, I don't think there is a clear case for fallacious reasoning on Carter's part... not based on this quote alone.

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Sam Carver
Sunday, June 16, 2019 - 06:25:21 PM
@Bo Bennett, PhD: Thank you very much for the input. Much appreciated.

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Keir Fabian
Wednesday, April 05, 2017 - 09:06:32 AM
What's the false dilemma in example #2?

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Bo Bennett, PhD
Wednesday, April 05, 2017 - 09:08:44 AM
Life is either the result of known natural processes, or it is the result of divine intervention. This excludes the option of unknown natural processes.

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Imran Shaik
Sunday, December 03, 2017 - 12:31:34 PM
@Bo Bennett, PhD: And in doing so you are committing false dichotomy fallacy.

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Bo Bennett, PhD
Sunday, December 03, 2017 - 12:32:58 PM
@Imran Shaik: Right. This is a demonstration of fallacious examples.

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irshad
Wednesday, January 24, 2018 - 09:43:15 PM
@Bo Bennett, PhD: in reality ,we don't know that how much we don't know.
there are known known in the universe
there are unknown known in the universe
there are known but we don't know holistic nature of.
it but i humbly feel creator is the best explanation
because we know the pixels but creator has the whole picture.

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Maromie
Saturday, November 24, 2018 - 02:05:46 PM
@irshad : Appeal to intuition is also a logical fallacy. Just because you feel good about the idea of something does not make it real.

It's also absurd that you make the claim that "the creator" has the whole picture when you haven't even demonstrated that there is a "creator" in the first place.

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Bruce
Saturday, February 16, 2019 - 06:47:17 PM
@irshad : It's not really the best explanation because it's something no one understands completely. It is an explanation though.
It is true there is much knowledge and we do not know how much we don't know. It's more of a perspective for those that believe a greater power is the only answer. In truth can not prove either the existence or non existence of a greater power because, like has been said, there is much we do not know.

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