Tag Archives: burden of proof

Appeal to Ignorance


by Tim Harding

The scope of the Appeal to Ignorance fallacy (Argumentum ad Ignorantiam in Latin) is more limited than its title would suggest. In the specific context of this fallacy, the word ignorance represents ‘a lack of contrary evidence’ rather than a lack of education or knowledge. The fallacy title was likely coined by the philosopher John Locke in the late 17th century.

In informal logic, this fallacy asserts that a proposition is true because it has not yet been shown to be false, or a proposition is false because it has not yet been shown to be true. This represents a type of false dichotomy, in that it excludes the possibility that there may have been an insufficient investigation to determine whether the proposition is either true or false. In other words, ‘absence of evidence is not evidence of absence.’

In rhetorical debates, appeals to ignorance are sometimes used in an attempt to shift the burden of proof.  A typical example is as follows: ‘In spite of all the talk, not a single flying saucer report has been authenticated. We may assume, therefore, there are no such things as flying saucers.’ An absurd but logically equivalent example is: ‘Although NASA has shown that the surface of the moon is not made of green cheese, it has not conclusively demonstrated that the Moon’s core is not made of it; therefore, the moon’s core is made of green cheese.

This fallacy is a potential trap that empiricists need to be wary of falling into. We cannot prove the non-existence of anything, so the burden of proof lies with those who claim the existence of something, rather than those who doubt it. So, we should always remain open to the possibility of new evidence in support of a claim, even if no such evidence has ever been found.

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Drange on methodological atheism

Methodological atheistsclaim that there is no good objective evidence either for God’s existence or for God’s nonexistence, but there is a certain methodological principle which places the burden of proof upon theists, and since they fail to meet that principle, the only rational position to take is that of atheism. (Some methodological atheists formulate the principle by saying that the burden of proof is always on any person making an existence claim, since, from a logical point of view, existence claims are only capable of proof, not disproof. No one has ever proven the nonexistence of Santa Claus, or elves, or unicorns, or anything else, simply because the very logic of an unrestricted existential proposition prohibits its disproof. It is impossible to go all over the universe and show that, for example, there are no elves anywhere. For this reason, rational methodology calls for us to deny the existence of all those things which have never been shown to exist. That is why we all regard it rational to deny the existence of Santa Claus, elves, unicorns, etc. And since God is in that same category, having never been shown to exist, it follows that rational methodology calls for us to deny the existence of God.)” –  Theodore M. Drange

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