Ignoratio

Ignoratio is a Latin term meaning ignorance. In logical usage, it appears most often as ignoratio elenchi, the fallacy of drawing a conclusion that is irrelevant to the issue under discussion. The premises may be true or sound, but the conclusion does not address the question at hand.

Definition and distinction: Ignoratio elenchi is a subtype of non sequitur. All ignoratio elenchi arguments are non sequiturs, because the conclusion does not follow from the premises. However, not all non sequiturs are ignoratio elenchi. The key feature is that the argument diverts to an unrelated conclusion rather than engaging with the original issue or claim.

Examples:

- A debate about climate policy yields the conclusion "Therefore we should ban all books," which has nothing to do with the policy under discussion.

- Premises mention wage data in support of a minimum-wage proposal, but the conclusion addresses the weather rather than the policy. This explicitly shifts to an irrelevant conclusion, missing the point of the argument.

Origin and usage: The phrase originates in Latin rhetorical and scholastic traditions and has been adopted into modern logic to classify arguments that fail to address the matter under consideration.

Related concepts: Ignoratio elenchi is related to the broader category of non sequiturs. It is distinct from red herrings, which deliberately distract by introducing an irrelevant point, and from straw man, which misstates an opponent’s argument.

In critique: Identifying ignoratio elenchi helps writers and readers focus on whether conclusions are properly supported by the relevant premises and whether the argument actually engages with the issue at hand.