The fallacy of argumentum ad consequentiam (or appeal to consequences) occurs when an arguer uses the desirability (or undesirability) of accepting a statement as evidence of its truth (or falsehood).

Here is an example:

Vacuum cleaner salesman: "My mother told me that 'honesty is the best policy,' but if I follow that then I won't be able to sell very many vacuum cleaners, which means that I'll be poor and lose my house, so, therefore, my mom's advice must be false.

The problem here is that the undesirable consequences described by the salesman do not necessarily falsify the statement in question. Instead, it may well be that honesty is, overall, the best policy, and that the salesmen would do well in the long run to find an honest way to sell vacuum cleaners.

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