When the conclusion does not follow from the premises. In more informal reasoning, it can be when what is presented as evidence or reason is irrelevant or adds very little support to the conclusion.
Examples:
- People generally like to walk on the beach. Beaches have sand. Therefore, having sand floors in homes would be a great idea!
Synonyms: derailment, “that does not follow, ” irrelevant reason, invalid inference, non-support, argument by scenario [form of], false premise [form of], questionable premise [form of]