(argumentum ad consequentiam, appeal to consequences of a belief, argument to the consequences)

This fallacy occurs when someone argues that something cannot be true because the consequences are unacceptable (or is true because the consequences are desirable). This is a fallacy for several reasons: 1) desirability is a subjective concept; 2) it seeks to convince through an emotional appeal as the consequences often evoke fear or desire; and 3) it is teleological in nature (reverses cause in effect) by asserting that something is caused by its own effect. The consequences of something are irrelevant to whether or not it actually exists; children may behave well if they believe in Santa, but that does not mean that Santa must exist.

Consequences can be taken into consideration when the argument is whether or not something is desirable, just not whether it is true. In trying to determine a plan of action, it is very reasonable to consider consequences (prescribing drugs, for example). However, that doesn’t mean that something must be false because it doesn’t work out how we want it to.

Examples:

“Evolution must be wrong because otherwise it would lead to immorality.”

“The universe has all the properties necessary to support life; therefore, it was designed specifically to support life (and therefore had a designer).”

“Racial integration is bad because we no longer maintain separate bathrooms and water fountains which results in job losses for plumbers.”

“Interracial marriage is bad because people of difference races have different faiths, and someone would have to give up their beliefs to make it work.”

“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.”

“An afterlife must exist; I want to exist forever.”

“An afterlife must not exist; I don’t want to live forever.”

“The axiom of choice must be wrong because it implies the Banach-Tarski paradox, meaning that geometry contradicts common sense.”

“Free will must exist: if it didn’t, we would all be machines.” (This is also a false dilemma.)

“Evolution must be false: if it were true then human beings would be no better than animals.”

“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.

“God must exist; if He did not, then people would have no reason to be good and life would have no meaning.”

“Objective morality must exist; if it didn’t, then it could be considered acceptable to commit atrocities.”

“The belief in the theory of evolution leads to eugenics; therefore, the theory of evolution is false.”

“Environmentalism leads to eugenics; therefore, global warming is false.”

“Belief in god leads to an increase in charitable giving; therefore god exists.”

“Global climate change cannot be caused by human burning of fossil fuels, because if it were, switching to non-polluting energy sources would bankrupt American industry.”

Some zoologists are saying the monkey is ancestor of the human. Then ask the scholar, “Sir, who is your grandfather? Is he a monkey? Then you are a descendant of a monkey.” Will he like that? No way. It will turn him off. Would you like a monkey to be your grandfather? Sun Myung Moon, Way Of Unification (Part 1)

From Henry M. Morris (The Remarkable Birth of Planet Earth, pp. vi-viii) “I want to list seventeen summary statements which, if true, provide abundant reason why the reader should reject evolution and accept special creation as his basic world-view…. 13. Belief in special creation has a salutary influence on mankind, since it encourages responsible obedience to the Creator and considerate recognition of those who were created by Him.… 16. Belief in evolution and animal kinship leads normally to selfishness, aggressiveness, and fighting between groups, as well as animalistic attitudes and behaviour by individuals.”

“The existence of gravity would make falling from a height onto a hard surface unpleasant, therefore gravity cannot exist.”

“Reducing greenhouse gas emissions would require policies we don’t like; therefore, anthropogenic greenhouse gasses don’t have any effect on the climate.”

“God must exist! If God did not exist, then all basis for morality would be lost and the world would be a horrible place!”

“It can never happen to me. If I believed it could, I could never sleep soundly at night.”

“I don’t think that there will be a nuclear war. If I believed that, I wouldn’t be able to get up in the morning. I mean, how depressing.”

“I acknowledge that I have no argument for the existence of God. However, I have a great desire for God to exist and for there to be an afterlife. Therefore I accept that God exists.”

“If believe in God then you’ll find a kind of fulfilment in life that you’ve never felt before; therefore, God exists.” (Pascal’s Wager)

“If you don’t believe in God then you’ll be miserable, thinking that life doesn’t have any meaning; therefore, God exists.” (Pascal’s Wager)

“If there is no objective morality, then all the bad people will not be punished for their bad behavior after death. I don’t like that; therefore, morality must be objective.” (Also begging the question)

In “The Matrix,” Neo is asked whether he believes in fate; he says that he doesn’t. He is then asked why, and replies, “I don’t like the thought that I’m not in control.” This is not an appeal to evidence, but to the unpleasantness of believing in fate: Fate would imply that the world is a way that I don’t want it to be, therefore there is no such thing.