A cogent argument fulfills the three criteria of having acceptable premises which are relevant to the conclusion and sufficiently support it. The irrelevant reason fallacy violates the relevancy criteria.
Also referred to in formal logic as a non-sequitur the irrelevant reason is a fallacy in which the conclusion does not follow from the premises. The two conditions for identifying the fallacy are:
1. The arguer has put forth a premise as a reason for the conclusion.
2. The premise, considered in conjunction with the other premises, fails to satisfy the relevance requirement.
For example, Marc Lalonde, the one time Canadian Minister of Health, responded to the charge of permitting the sale of Kellogg's Corn Flakes which had little or no nutritional value by saying:
"As for the nutritional value of Corn Flakes, the milk you have with your Corn Flakes has great nutritional value."
The implication is that since (1) the milk you have with your cereal has great nutritional value, therefore (2) Kellogg's Corn Flakes has great nutritional value. Of course the two are separate food items and to determine the nutrient value of any food, one needs to measure the value of the food itself and not include the value of a companion food which may be consumed with it. As such,