Logical & Critical Thinking

with Professor Logic

Argumentum Ad Ignorantiam

argumentum-ad-ignorantiamThe Argumentum Ad Ignorantiam is where one assumes a thing is true if it cannot be proven to be false or that a thing is false if it cannot proven to be true. In both directions a fallacy has occurred because in the absence of evidence no conclusion can be drawn.

If these arguments were logical and compelling cases for beliefs then any fantasy story could be declared true and be valid simply because it could not be proven wrong. Let your imagination wander and you can see the silliness this type of thinking could produce.

Argumentum Ad Ignorantiam Example

Argumentum Ad Ignorantiam Example 1

Fallacy: God doesn’t exist because there is no evidence for it.

Actuallity: God may exist and merely not having evidence for it does not mean it does not exist, although there is also no reason to believe a thing in the absence of evidence.

Argumentum Ad Ignorantiam Example 2

Fallacy: God exists and you have to prove that god doesn’t exist.

Actuality: One does not have to prove a belief with no evidence to be wrong, in the absence of evidence there is no reason to believe a thing.

Negative Proof Fallacy Logic Structure

A is true and it is true till proven false

A is false and it is false till proven true

Negative Proof Fallacy Helpful Links

  • WilliamOckhamensis

    Any proof for or against the existence of God requires two terms to be defined, God and existence. William of Ockham defined three kinds of existence: “in nomine”, “in intellectu” and “in re” – as a mere name, empty of content; as a concept; or as a real thing. THe God of the bible clearly does exist in nomine and in intellectu, but there is no evidence that he exists in re. On the contrary, since many of the things attributed to him in the Old Testament and offered as proof of his existence clearly could not have happened (such as the flood story), his existence in re has the status of a falsified hypothesis. That of course is not enough to satisfy the purists, who mumble about the inductive fallacy, but it is good enough for us empiricists. The existence in re of the God of the bible is empirically so highly improbable that it can be ruled out as a useful hypothesis. Along with other hypotheses that cannot be disproved except on empirical grounds, for example, that the earth is flat.

  • WilliamOckhamensis

    Love your site btw