Although there are many things wrong with the witch trials, they are a great example of the appeal to ignorance fallacy. Is someone a witch if we can’t prove that they are not a witch? In informal logic this fallacy is also known as argument from ignorance or argumentum ad ignorantiam.
This fallacy occurs when an argument states that something is true just because we don’t know it to be false. Or, something is true because we don’t have any proof that shows it to be false. This fallacy goes vice versa, change “true” and “false” in the previous definition, it still represents a fallacious argument.
Example:
“There would have been evidence of alien life in the galaxy. Therefore, they don’t exist.”
The speaker makes an argument that aliens don’t exist based on the lack of evidence for the opposite argument. Therefore, the fallacy occurs. Ignoring one lack of evidence and taking another as a premise. However, the lack of evidence does not disprove the existence of alien life.
There is still the possibility that aliens haven’t been able to reach yet. Some argue that our knowledge can’t go that far. Of course, scientists do agree that the presence of alien life in the galaxy is not an unreasonable theory. Until there’s affirming evidence for one side of the argument, the territory remains speculative.
So, there are two main characteristics to the argumentum ad ignorantiam. The first is lack of evidence, we mistake it for disapproving evidence, and use it as basis for a conclusion. The other one is replacing knowing with proof.
Logic:
~[proof that p]→ ~p
~[proof that ~p] →p
Or:
Lack of evidence for X or no proof for X to be true→X is false
Lack of evidence for X or no proof for X to be false→X is true
The fallacy can take the form of a question:
- Speaker A: There is a reincarnation of a man in every dog’s brain.
- Speaker B: Really? How do you know that’s true?
- Speaker A: How do you know it’s not?
Although Speaker A puts forward an interesting proposition, when faced with presenting proof, he disappoints. Even if Speaker B can’t present proof that no man resides in a dog’s brain, it’s fallacious to take the lack of evidence for the opposite as a premise.
It begs the question, can an argument based on a lack of evidence not be fallacious? The accused are innocent until proven guilty of course. Does the fallacy occur here? Only in a formal sense, it’s from experience that we know alternative ways of prosecuting someone is ineffective.
Scientists have allowed leniency in this argument in the past. The lack of evidence for the existence of King Arthur, is taken as evidence enough for the opposite. Science has progressed that much that when it’s stating something it presents excruciating evidence. At least, it presents probability.
An argument from ignorance can be formed intentionally as a way to point out the difficulty of really knowing something. Skeptics used this against dogmatic statements. They were opposed to the possibility of knowing something with certainty. Although ineffective in finding out new knowledge, they opened up some existing problems in the understanding of truth.
Skeptic Example:
Simulated reality hypothesis:
“We may be living in a simulated reality very similar to ours, we can’t recognize it or we are being deceived.”
Nowadays, when you think of simulated reality, you think of the movie Matrix. But this argument was made by Descartes in his “Meditations”. Descartes was asking if he can doubt the existence of a God who is deceiving him. Of course, this argument is used as a way to point out the uncertainty of knowledge. It’s still appealing to the lack of evidence for the opposite argument.
Skeptics raise a good point, consider this:
Example:
- Speaker A: I’m telling you man, the Illuminati are real.
- Speaker B: How do you know?
- Speaker A: No one has proven otherwise.
There’s a chance that Speaker A has watched too many YouTube videos about conspiracy theories. Nonetheless, Speaker B is what this example is about. How do we know? This is a big question in epistemology. Would you consider a product sugarless without the nutrition label? That nutrition label is proof. So, it would seem we need positive proof in order to know.
But what do we consider as positive proof? Looking for positive proof in everyday life is ridiculous, normally, people base their knowledge on authorities. This is not the problem at hand though. Those with truth as their profession, don’t always agree that proof is enough in order to know.
When scientists say they know something with certainty or probability, they know it through experiments which are inspected with the language of logic. Even after then, some will restrict their statements with “as the object appears to us”, “to our understanding”.
The definition of truth and the difficulty of knowing something with certainty has bothered thinkers for more than 2,000 years. What we consider as the basis for truth has changed over the years. There are alternative theories of truth, scientists calculate probability, new logic systems are formed.
The absurdity of argumentum ad ignorantiam is thus clear. Using lack of evidence as a premise can’t hold a place when we argue something to be true or false. There are other tools that can be used for inspecting the truth. When we have no scientific way of inspecting something, we use dialectics, however, appealing to ignorance blocks the argument.