LOGIC & ARGUMENT

Inductive and deductive reasoning. Fallacious argumentation versus sound argumentation

 Recognize the elements of persuasive writing and use them.

 Criticize bad argumentation pointing out the weaknesses.

 Identify commonly used fallacies that contribute to weak argumentation.

 Recognize well reasoned argumentation.

Topics

 Cheating is justified because polygamy is inherent to the male species.  A Coalition Government is necessary to break the political deadlock in Guyana, and will ensure will a bright future for the country.

 The interfaith movement is the solution to religious and social turmoil.  Prostitution should be legalised in Guyana.  Homosexuality should be legalised in Guyana.

    Logic is a formal system of analysis that helps writers invent, demonstrate, and prove arguments. It works by testing propositions against one another to determine their accuracy.

Unemotional or common sense statements are not always equivalent to logical statements. To be logical, a proposition must be tested within a logical sequence.

  

Syllogism Illogical Fallacious

 ◦ Logic can also mislead when it is based on premises that an audience does not accept.

Premise 1: People with red hair are not good at checkers.

Premise 2: Bill has red hair.

Conclusion: Bill is not good at checkers.

– P1: All men are dogs – P2: Kencil is a man – Concl: Kencil is a dog – P1: All birds can fly – P2: The penguin is a bird – Concl: The penguin can fly

• • • • To be logical, a proposition must be tested within a logical sequence.

The most famous logical sequence, called the syllogism, was developed by the Greek philosopher Aristotle. His most famous syllogism is: Premise 1: All men are mortal.

Premise 2: Socrates is a man.

Conclusion: Therefore, Socrates is mortal.

In this sequence, premise 2 is tested against premise 1 to reach the logical conclusion.

Argument

  A logical arguments appeals to the intellect (reason); A persuasive argument appeals to the emotions.

Argument

   Arguments are usually like expositions which make use of facts. Expositions are usually about subjects on which people agree.

Arguments are usually about subjects on which people do not agree.  An argument has a set of claims (at least two), one of which is the major claim or conclusion, while the other claim(s) are the grounds which supposedly support or justify the conclusion.

 “But tourism also has unfortunate side effects. Look what has happened in other parts of the world where tourists congregate – the crime rate soars, moral standards become lower, and social problems arise”   TWO claims: One is the conclusion, “But tourism has unfortunate side-effects”; The rest of the argument is the grounds on which the conclusion is based.

   “How can you agree that a foetus is human from the moment of conception? A man is legally dead when he is brain dead. A foetus should not be considered alive until it has a fully developed brain.” THREE claims: 1 st sentence is the conclusion; Other two sentences justify the conclusion

Against legalizing prostitution   Legalizing prostitution will do more harm than good not only to society but to the nation as well. [Conclusion] Clients “partners they are having sex with” do not have to provide certification/mention of diseases. “They may have a transferable disease”. [Justification]

Fallacies

• • Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim.

Avoid these common fallacies in your own arguments and watch for them in the arguments of others.

Slippery Slope

• • This is a conclusion based on the premise that if

A happens, then eventually through a series of small steps, through B, C,..., X, Y, Z will happen,

too, basically equating A and Z. So, if we don't want Z to occur, A must not be allowed to occur either. –

If we ban Hummers because they are bad for the environment eventually the government will ban all cars, so we should not ban Hummers.

In this example the author is equating banning Hummers with banning all cars, which is not the same thing.

Hasty Generalisation

• This is a conclusion based on insufficient or biased evidence. In other words, you are rushing to a conclusion before you have all the relevant facts. –

Even though it's only the first day, I can tell this is going to be a boring course.

Post hoc ergo propter hoc Faulty Cause-Effect Relationship

• • • • This is a conclusion that assumes that if 'A'

occurred after 'B' then 'B' must have caused 'A.‘

I drank bottled water and now I am sick, so the water must have made me sick.

Every time cricket is played at Bourda we experience heavy rainfall. The increase in explicit violence on television is making the crime rate soar.

Begging the Claim

• The conclusion that the writer should prove is validated within the claim. – Filthy and polluting coal should be banned. Arguing that coal pollutes the earth and thus should be banned would be logical. But the very conclusion that should be proved, that coal causes enough pollution to warrant banning its use, is already assumed in the claim by referring to it as "filthy and polluting.”

Either/Or

• • • • This is a conclusion that oversimplifies the

argument by reducing it to only two sides or choices.

We can either stop using cars or destroy the earth. In Guyanese politics, you’re either PPP or PNC. It’s either me or she.

Circular Argument

• • •

This restates the argument rather than actually proving it.

(Arguing in circles)

President Obama is a good communicator because he speaks effectively.

Ad hominem

• This is an attack on the character of a person rather than her/his opinions or arguments.

Red Herring

• This is a diversionary tactic that avoids the key issues, often by avoiding opposing arguments rather than addressing them.

– The level of mercury in seafood may be unsafe, but what will fishers do to support their families?

(Movement away from the safety of food to another issue.)

Ad Populum

•

This is an emotional appeal that speaks to

positive (such as patriotism, religion, democracy) or negative (such as terrorism or fascism) concepts rather than the real issue at

hand.

– If you were a true American you would support the rights of people to choose whatever vehicle they want.

– If you was a real man, you wouldn’t tek duh.

Genetic Fallacy

• A conclusion is based on an argument that the

origins of a person, idea, institute, or theory

determine its character, nature, or worth.

–

The Volkswagen Beetle is an evil car because it was originally designed by Hitler's army.

In this example the author is equating the character of a car with the character of the people who built the car. However, the two are not inherently related.

Moral Equivalence

•

This fallacy compares minor misdeeds with major atrocities.

– That parking attendant who gave me a ticket is as bad as Hitler.

Bandwagon

• • “consensus of the people” A bandwagon argument tries to convince you everyone else agrees with the idea already, so you ought to join in. •

Each year an increasing number of people quit smoking, so you ought to quit too.

False Analogy

• Things at first glance may seem to be comparable but really are not. • • Raising the national speed limit is like offering free cocktails at a meeting of recovering alcoholics. Drivers aren’t recovering from an addiction to high speed driving.