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Appeal to consequences, also known as argumentum ad consequentiam (Latin for argument to the consequences), is an argument that concludes a premise (typically a belief) to be either true or false based on whether the premise leads to desirable or undesirable consequences. This is based on an appeal to emotion and is a form of logical fallacy, since the desirability of a consequence does not address the truth value of the premise. Moreover, in categorizing consequences as either desirable or undesirable, such arguments inherently contain subjective points of view.

In logic, appeal to consequences refers only to arguments which assert a premise's truth value (true or false) based on the consequences; appeal to consequences does not refer to arguments that address a premise's desirability (good or bad, or right or wrong) instead of its truth value. Therefore, an argument based on appeal to consequences is valid in ethics, and in fact such arguments are the cornerstones of many moral theories, particularly related to consequentialism.

General form

An argument based on appeal to consequences generally has one of two forms^[1]:

Positive form

If P, then Q will occur.

Q is desirable.

Therefore, P is true.

It is closely related to wishful thinking in its construction.

Examples

• "Pi is probably a rational number: being rational would make it more elegant."
• "Real estate markets will continue to rise this year: home owners enjoy the capital gains."
• "Humans will travel faster than light: faster-than-light travel would be beneficial for space travel."
• "God must exist because how could morality exist without him?"

Negative form

If P, then Q will occur.

Q is undesirable.

Therefore, P is false.

Appeal to force (argumentum ad baculum) is a special instance of this form.

This form somewhat resembles modus tollens but is both different and fallacious, since "Q is undesirable" is not equivalent to "Q is false".

Examples

• "The axiom of choice must be wrong because it implies the Banach-Tarski paradox, meaning that geometry contradicts common sense."
• "Atheism must be erroneous: it denies eternal happiness after death."
• "Free will must exist: if it didn't, we would all be machines." (also a False Dichotomy)
• "If the six men win, it will mean that the police are guilty of perjury, that they are guilty of violence and threats, that the confessions were invented and improperly admitted in evidence and the convictions were erroneous... This is such an appalling vista that every sensible person in the land would say that it cannot be right that these actions should go any further." Lord Denning in his judgment on the Birmingham Six.

Notes

1. ^ FallacyFiles.org - Appeal to Consequences

See also

• Affirming the consequent
• Appeal to fear
• Wishful thinking
• Argumentum ad hominem circumstantial form
• List of logical fallacies
• Pascal's Wager
• utilitarianism