Argument from Ignorance (Argumentum ad Ignorantiam)
An argument from ignorance treats a claim as true because it has not been disproved, or as false because it has not been proved. Either inference needs more than a bare lack of proof.
THE IDEA
2.3 ARGUMENTUM AD IGNORANTIAM
Argumentum ad ignorantiam is Latin for "argument from ignorance." The fallacy treats the absence of proof as a conclusive answer. It can work in either direction: a claim is declared false because it has not been proved, or true because it has not been disproved.
The structure of this argument takes the following form:
- Premise: There is no evidence or proof for x.
- Conclusion: x is false; x should be dismissed; or, x has been refuted.
The argumentum ad ignorantiam fallacy is quite common in religious discussions. Consider this example:
- The existence of God has never been disproved. Therefore, God must exist.
One of the serious problems with the ad ignorantiam fallacy is that in many cases its opposite can be argued in the same manner. For example:
- The existence of God has never been proven. Therefore, God does not exist.
Simply because there is not verifiable evidence that a certain thing exists, this does not mean that its existence should be dismissed or not taken seriously. More importantly, we must remember that a lack of proof is not a refutation.
Here are three final examples:
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Candidate Smith has never spoken out concerning her views on abortion. We can safely conclude that she must be pro-choice.
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There is no proof that extraterrestrials exist. Therefore, they must be figments of our imagination.
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Since we have no physical evidence supporting the claim that Socrates was a real person, he must have never existed.
These examples draw a definite conclusion from missing evidence. Ask whether the evidence should have been observable if the claim were true. Its absence may then count against the claim; otherwise, withholding judgment may be the appropriate response.
When to use it
Evaluating claims in religious or metaphysical debates where evidence is limited.
Assessing arguments in courtrooms where lack of evidence is used to assert innocence or guilt.
Critical thinking about conspiracy theories that rely on 'no proof' to dismiss mainstream explanations.
Making informed decisions in science when faced with untested hypotheses or insufficient data.
FROM THEORY TO EVERYDAY LIFE
In practice
God's existence (pro and con)
Example 1: 'The existence of God has never been disproved. Therefore, God must exist.' Example 2: 'The existence of God has never been proven. Therefore, God does not exist.' Both commit the fallacy by using lack of evidence to draw a definitive conclusion.
Candidate Smith's views
Candidate Smith has never spoken out concerning her views on abortion. We can safely conclude that she must be pro-choice. This uses lack of public statement as evidence for a specific position.
Extraterrestrials
There is no proof that extraterrestrials exist. Therefore, they must be figments of our imagination. The absence of proof is taken as disproof.
Socrates' historicity
Since we have no physical evidence supporting the claim that Socrates was a real person, he must have never existed. This dismisses historical evidence beyond physical artifacts.
A MOMENT TO REFLECT
Put it to work.
Can you recall a time when you accepted or used an argument from ignorance? What was the outcome?
How would you respond to someone who says 'There's no evidence that this treatment works, so it must be ineffective'?
Why is it important to distinguish between 'not proven' and 'disproven' in scientific and legal reasoning?
CONTINUE THE CONVERSATION
Source texts
- Informal Logical Fallacies A Brief Guide