1. Argument ad Ignorantiam
John and Seanne

2. Argument ad Ignorantiam: saying something is true only because there is no evidence to prove it wrong (or saying something is false only because there is no evidence to prove it is true)
“Ad Ignorantiam” means “appeal to ignorance” in Latin
Argument ad Ignorantiam is also known as “argument from ignorance” or “argument from lack of imagination”

3. Argument ad Ignorantiam can be expressed in multiple ways, including the following:
One cannot prove that this is true, therefore it is false.
No one observed this occur, therefore it did not occur.
There is no proof to support Argument X, therefore Argument Y is true.

4. The two most common forms (both examples of fallacious reasoning) are:
1. Something is untrue because there is currently insufficient evidence or explanation corroborating it
2. Due to a lack of sufficient evidence/explanation for one hypothesis, a different hypothesis must be correct

5. Burden of Proof
The burden of proof is an important thing to establish in regards to argument ad Ignorantiam.
Whomever the burden of proof falls on should provide proof to support their argument
Some suggest that the burden of proof should fall on the person trying to prove an argument, others that it should fall on the one trying to disprove it
Regarding argument ad Ignorantiam, there is no proof required, merely the lack of it, to verify an argument – which is illogical and fallacious

6. Common Occurrences of Argument Ad Ignorantiam
This form of argument is widely used by many Creationists /followers of the Intelligent Design theory to negate evolution, in the manner of “One cannot prove evolution has occurred, therefore it is true that God created the world.”
Similarly, you can argue that one cannot prove that God does not exist, therefore he/she/it must exist.
DISCLAIMER: this is not to suggest all arguments put forth by religious persons are examples of argument ad Ignorantiam.

7. More Common Occurrences
In most modern criminal courts (e.g. the United States), the accused is considered innocent until proven guilty, which means the burden of proof lies on the prosecution to prove beyond reasonable doubt that the alleged perpetrator has committed the crime. This due in part to the reasoning against “argument ad Ignorantiam”: the lack of evidence of innocence is not enough to indicate guilt

8. Examples
John says ghosts exist. Seanne disagrees and says that ghosts don’t exist John says that Seanne can’t prove him wrong and he is therefore right…as usual. (a common example of John’s arguing tactics) Seanne says that the world as we perceive it is most likely real John says we cannot prove it, therefore life must be a dream.