Fallacies in Logic ~ Reductio ad Absurdum

Reductio ad Absurdum

reductio ad absurdum

(also known as: reduce to absurdity)

 

Description: A mode of argumentation or a form of argument in which a proposition is disproven by following its implications logically to an absurd conclusion.  Arguments which use universals such as, “always”, “never”, “everyone”, “nobody”, etc., are prone to being reduced to absurd conclusions.  The fallacy is in the argument that could be reduced to absurdity -- so in essence, reductio ad absurdum is a technique to expose the fallacy.

 

Logical Form:

Assume P is true.

From this assumption, deduce that Q is true.

Also deduce that Q is false.

Thus, P implies both Q and not Q (a contradiction, which is necessarily false).

Therefore, P itself must be false.

 

Example #1:

I am going into surgery tomorrow so please pray for me.  If enough people pray for me, God will protect me from harm and see to it that I have a successful surgery and speedy recovery.

 

Explanation: We first assume the premise is true: if “enough” people prayed to God for her successful surgery and speedy recovery, then God would make it so.  From this, we can deduce that God responds to popular opinion.  However, if God simply granted prayers based on popularity contests, that would be both unjust and absurd.  Since God cannot be unjust, then he cannot both respond to popularity and not respond to popularity, the claim is absurd, and thus false.

 

Example #2:

If everyone lived his or her life exactly like Jesus lived his life, the world would be a beautiful place!

 

Explanation: We first assume the premise is true: if everyone lived his or her life like Jesus lived his, the world would be a beautiful place.  If this were true, we would have 7 billion people on this earth roaming from town to town, living off the charity of others, preaching about God (with nobody listening). Without anyone creating wealth, there would be nobody to get charity from -- there would just be 7 billion people all trying to tell each other about God.  After a few weeks, everyone would eventually starve and die.  This world might be a beautiful place for the vultures and maggots feeding on all the Jesus wannabes, but far from a beautiful world from a human perspective.  Since the world cannot be both a beautiful place and a horrible place, the proposition is false.

Source:

 

https://www.logicallyfallacious.com/tools/lp/Bo/LogicalFallacies/151/Reductio-ad-Absurdum

Comments:

 

Example #2 fails to inform on what would God do in the case that all men/women pursued Him in the spiritual life like Christ showed. When we live the spiritual life, is not God invoked to live in us and therefore are we not in paradise at that exact moment? So imagine a movement where all live spiritually and live in that exact moment in Paradise, paradise not as a place but as "being" as "disposition." Wealth is no longer created nor hoarded nor needed. Far from people starving to death, we would be feeding off of theoria or the nous... God would feed us noetically and paradise would be restored. There would be no more fear or need of anything, no passions, no bondage, and no more slavery to anything material: sex, drugs, power, wars for lands, etc. Here, in plain view, is the shortcoming of man's logic and from here we can begin to contemplate the intellect of man as understood in the Philokalia, not rational mind but noetic intellect that transcends to the heights; here God comes down to illuminate and divinize mankind. Example #2 clearly forgets or does not consider God's way and logic, but only man's reasoning, which as the times and histories have shown, repeatedly, will forever remain imperfect, unfulfilling, and impermanent. And what is impermanent is sure to change and pass away. This is faith and will come up fallacious in the games of logic, but nonetheless, it remains as a player as testified by countless saints throughout time/space. We can dismiss it, pooh-pooh it, but then like the yin-yang symbol shows, the circle is not complete without the Divine (Heaven) realm.

 

 

 

 

moreover...

Reliance on the Principle of Non-Contradiction
One of the assumptions of the reductio argument form is that claims which entail a contradiction entail an absurd or unacceptable result. This relies on the 'principle of non-contradiction,' which holds that for any claim 'p,' it cannot be the case both that p is true and p is false. With this principle, one can infer from the fact that some set of claims entail a contradictory result (p and not-p) to the fact that that set of claims entails something false (namely, the claim that p and not-p). Though the principle of non-contradiction has seemed absolutely undeniable to most philosophers (the Leibnizian eighteenth-century German philosopher Christian Wolff attempted to base an entire philosophical system on it), but some historical figures appear to have denied it (arguably, Heraclitus, Hegel and Meinong). In more recent years, using the name 'dialetheism,' philosophers such as Graham Priest and Richard Routley have argued that some contradictions are true (motivated by paradoxes such as that posed by the statement, "this sentence is not true").
If the law of non-contradiction is false, then it can be the case that some contradictions are true. In that case, at least some instances of reductio arguments will fail, because the assumed claims will fail to yield anything absurd. Despite this philosophical possibility, the law of non-contradiction, and so the formal legitimacy of all reductio arguments, are still almost universally accepted by logicians. In some logical systems, the reductio form has been used as a basis for introducing a negation operator.

Source:

http://www.newworldencyclopedia.org/entry/Reductio_ad_absurdum

 

 

Examples and Observations

• "The basic idea of the argumentum ad absurdum is that if one can show that a belief leads to an obvious absurdity, then the belief is false. Thus, assume someone believed that being outside with wet hair caused sore throats. You could attack this belief by showing that if it were true that being outside with wet hair caused sore throats, then it would also be true that swimming, which involves getting wet hair, caused sore throats. But since it is absurd to say that swimming causes sore throats, it is false to say that being outside with wet hair causes sore throats."
  (Christopher Biffle, Landscape of Wisdom: 

 

Examples of Reductio ad Absurdum Arguments- "Reductio ad absurdum. A 'reducing to absurdity' to show the falsity of an argument or position. One might say, for instance that the more sleep one gets the healthier one is, and then, by the logical reductio ad absurdum process, someone would be sure to point out that, on such a premise, one who has sleeping sickness and sleeps for months on end is really in the best of health. The term also refers to a type of reductive-deductive syllogism:

Major premise: Either A or B is true.
Minor premise: A is not true.
Conclusion: B is true."

(William Harmon and Hugh Holman, A Handbook to Literature, 10th ed. Pearson, 2006)

 

- "This strategy is illustrated in a Dilbert cartoon from April 1995. The pointy-haired boss announces a plan to rank all of the engineers 'from best to worst' so as 'to get rid of the bottom 10%.' Dilbert's co-worker Wally, included in the bottom 10%, responds that the plan is 'logically flawed' and proceeds to extend the range of his boss's argument. Wally asserts that the boss's plan, if made permanent, will mean continual dismissals (there will always be a bottom 10%) until there are fewer than 10 engineers and the boss will 'have to fire body parts instead of whole people.' The boss's logic will, Wally maintains (with a touch of hyperbole), lead to 'torsos and glands wandering around unable to use keyboards . . ., blood and bile everywhere!' These horrendous results will be the consequence of extending the boss's line of argument; hence, the boss's position should be rejected."
(James Jasinksi, Sourcebook on Rhetoric: Key Concepts in Contemporary Rhetorical Studies. Sage, 2001)


- "Reductio ad absurdum is a good and necessary way to work through the logical implications of a position. Most of Plato's Republic is an account of Socrates' attempts to guide listeners to the logical conclusions of their beliefs about justice, democracy, and friendship, among other concepts, through extended bouts of reductio ad absurdum. The United States Supreme Court also used this technique when it handed down its ruling in the famous 1954 case of Brown v. Board of Education. . . . While reductio ad absurdum can lead to long and complex arguments, it is often quite simple and practically useful. Take the following conversation as an example:

Mother (seeing her child take a rock from the Acropolis): You shouldn't do that!
Child: Why not? It is just one rock!
Mother: Yes, but if everyone took a rock, it would ruin the site!

. . . As you can see, reductio ad absurdum can be remarkably effective, whether in complex judicial arguments or in everyday conversations.

"However, it is easy to move from reductio ad absurdum to what some people call the slippery slope fallacy. The slippery slope fallacy uses a logic chain similar to that employed in reductio ad absurdum that makes unreasonable logical jumps, many of which involve so-called 'psychological continuums' that are highly unlikely."
(Joe Carter and John Coleman, How to Argue Like Jesus: Learning Persuasion from History's Greatest Communicator. Crossway Books, 2009)

 

Evaluating a Reductio ad Absurdum Argument"[A] reductio ad absurdum argument tries to show that one claim, X, is false because it implies another claim Y, that is absurd. To evaluate such an argument, the following questions should be asked:

1. Is Y really absurd?
2. Does X really imply Y?
3. Can X be modified in some minor way so that it no longer implies Y?

If either of the first two questions is answered in the negative, then the reductio fails; if the third question receives an affirmative answer, then the reductio is shallow. Otherwise, the reductio ad absurdum argument is both sucessful and deep."
(Walter Sinnott-Armstrong and Robert Fogelin, Understanding Arguments: An Introduction to Informal Logic, 8th ed. Wadsworth, 2010)

 

Adams Sherman Hill on Reductio ad Absurdum (1895)
"An argument which can be answered by reductio ad absurdum is said to prove too much--that is, too much for its force as an argument; since, if the conclusion is true, a general proposition which lies behind it and includes it is also true. To show this general proposition in its absurdity is to overthrow the conclusion. The argument carries in itself the means of its own destruction. For example:

(1) Skill in public speaking is liable to great abuse; it should, therefore, not be cultivated.
(2) Skill in public speaking is liable to great abuse; but so are the best things in the world--as health, wealth, power, military skill; the best things in the world should, therefore, not be cultivated.

In this example, the indirect argument under (2) overthrows the direct argument under (1) by bringing into view the general proposition omitted from (1) but implied in it--namely, that nothing which is liable to great abuse should be cultivated. The absurdity of this general proposition is made apparent by the specific instances cited.

"The argument that games of football should be given up because players sometimes sustain severe injuries may be disposed of in a similar way; for horseback-riders and boating-men are not exempt from danger.

"In Plato's dialogues, Socrates often applies reductio ad absurdum to the argument of an opponent. Thus, in 'The Republic,' Thrasymachus lays down the principle that justice is the interest of the stronger. This principle he explains by saying that the power in each State is vested in the rulers, and that, therefore, justice demands that which is for the interest of the rulers. Whereupon Socrates makes him admit that it is just for subjects to obey their rulers, and also that rulers, not being infallible, may unintentionally command that which is to their own injury. 'Then justice, according to your argument,' concludes Socrates, 'is not only the interest of the stronger but the reverse.'

"Another example of reductio ad absurdum is furnished by the reply to the arguments which attempt to prove by means of an alleged cipher that Bacon wrote the plays attributed to Shakspeare. All the arguments adduced in favor of this proposition may, as its opponents contend, be used to prove that anybody wrote anything."
(Adams Sherman Hill, The Principles of Rhetoric, rev. edition. American Book Company,

1895)

The Lighter Side of Reductio ad AbsurdumLeonard: Penny, if you promise not to chew the flesh off our bones while we sleep, you can stay.
Penny: What?
Sheldon: He's engaging in reductio ad absurdum. It's the logical fallacy of extending someone's argument to ridiculous proportions and then criticizing the result. And I do not appreciate it.
("The Dumpling Paradox." The Big Bang Theory, 2007)
Pronunciation: ri-DUK-tee-o ad-ab-SUR-dum


source:

https://www.thoughtco.com/reductio-ad-absurdum-argument-1691903


Examples of arguments using reductio ad absurdum are as follows:

• The Earth cannot be flat, otherwise we would find people falling off the edge.
• There is no smallest positive rational number, because if there were, then it could be divided by two to get a smaller one.

source:
https://en.wikipedia.org/wiki/Reductio_ad_absurdum


Reductio Ad Absurdum

Reductio Ad Absurdum is disproving an argument by showing the absurdity of following it through to a logical conclusion. Essentially, the argument is reduced to its absurdity. This works only if there is faulty logic in the argument to begin with.

Examples of Reductio Ad Absurdum:

In a location where there is a sign saying not to pick the flowers, a small child says to his mother, "It's just one flower."
Mother responds, "Yes, but if everyone who came by picked just one flower, there would be none left."
Your friend says, "If I rub my lucky rabbit's foot, then I will do well on this test."
You respond, "So, if it brings good luck, then I need to rub it so that my mom's cancer will go away, and my dad will get a new job, and our family will win the lottery.
You are in trouble for skipping school, but you tell your father, "All of my friends were going!"
He says, "Well, if all of your friends were going to jump off of a bridge, would you do that, too?"

Example of Reductio Ad Absurdum from Literature
From Jonathan Swift's A Modest Proposal:
I think it is agreed by all parties, that this prodigious number of children in the arms, or on the backs, or at the heels of their mothers, and frequently of their fathers, is in the present deplorable state of the kingdom... cheap and easy method of making these children sound and useful members of the common-wealth, would deserve so well of the public, as to have his statue set up for a preserver of the nation.


source:

http://softschools.com/examples/literary_terms/reductio_ad_absurdum_examples/337/