- The Nature of an Argument
- What is an argument?
- Deductive vs inductive reasoning
- Critical Thinking
- Common Fallacies
- What is a fallacy?
- Some fallacies are so well known that they have a name.
- Political rhetoric 101
- Picking Apart Your Opponent
- Hidden assumptions
- Implicit values
- Hidden agendas
- The Nature of an Argument(top)
- What is an argument
- By "argument" I don't mean a heated verbal dispute, but rather a written or spoken attempt to prove some claim through the use of reason.
- Using reason:
Attacking or upholding an argument.
- Traditionally an argument is shown with the following form:
- If the conclusion logically follows from the premises, we say that the argument is valid.
- This form is a bit stuffy and academic. Let's put it this way:
- We might say that if the reasons justify the claim, the argument is valid.
- Important! Strictly speaking, we say that an argument is valid if the conclusion logically follows from the premises. For example, this argument is logically valid:
- On the other hand, both premises are factually incorrect, so the conclusion, though valid, is nonsense.
Deductive vs inductive reasoning
- We can dispute the correctness of a claim (ie, tell our adversary that he or she is wrong) using two general approaches.
- We can dispute the factual accuracy of the premises.
- We can dispute the logical validity of the reasoning.
- There are two basic types of logical arguments.
- Deductive reasoning
- Inductive reasoning
- A valid deductive argument is logically inevitable.
- The simplest form might be:
- Pretty boring, huh? Notice that it is logically impossible for the conclusion to be false and all of the premises to be true.
- The example about whales above is another example of deductive reasoning.
- Mathematics is a very elaborate system of deductive reasoning.
Critical Thinking (top)
- An inductive argument is not logically inevitable even they are reasonable and compelling.
- An inductive argument always has to be hedged with words like "probably" or "most likely."
- Here is a fishy example:
Most fish lay eggs.
Salmon are fish.
Therefore, salmon probably lay eggs.
- In this example, it is logically possible for the premises to be true and for the conclusion to be false. Substitute Mako shark for salmon, and this would be the case.
- Science can be viewed as a huge set of inductive conclusions.
- Bernstein suggests five questions to ask about any claim. These are a good general approach when you are asked to believe something (or buy something).
Five Questions to Promote Critical Thinking:
What exactly am I being asked to believe or accept?
What evidence, if any, is there to support the claim?
Are there alternative (perhaps more plausible or simpler) ways of interpreting the evidence?
What additional evidence would help you choose between the alternatives?
What conclusion is most reasonable based on presently available evidence?
- This general critical approach can be supported by a thorough and reasonable or logical analysis of the evidence offered for a claim. See the 7 Questions below.
- What is a fallacy?
- A fallacy is a misleading argument: it seems correct but isn't.
Some fallacies are so well known that they have a name.
- These are very common in speech and writing.
- Sometimes, speakers (such as politicians or advertisers) use them on purpose to mislead people.
- Red herring
- An irrelevant issue brought up to distract from the main one:
- "Why should I quit smoking when all the pesticides in our food cause cancer?"
Two wrongs (still don't make a right)
- A extreme alternative that jumps over any middle ground:
- "You don't like me coming in to class at 6:15? What do you want me to do, get here at noon?"
Appeal to authority
- Everybody does it:
- "It's ok to cheat on your tax return, even federal judges do that."
- So what?
- "Why bother to reduce the violence on TV? Kids can learn how to make bombs from the Internet."
- Basing an argument on the status of a person or group rather than on its own merits:
- "Four out of five dentists recommend Trident for their patients who chew gum."
- Some folks claim that education is based entirely on the appeal to authority: Students are led to believe that what they read in their text books is the absolute truth.
- "My English teacher told me that Shakespeare was the greatest writer of all time."
- Combining more than one question into a single one that cannot be safely answered either way:
- "Have you stopped cheating on Psychology quizzes?"
- Ad hominem arguments
- The opposite of appeal to authority, this is attacking the arguer rather than the argument:
- "'Psychology is fun?' You can't believe anything that an idiot like Benoit would tell you."
Political rhetoric 101
- This is a little like a red herring, though more elaborate. In this case, an opponent's argument is intentionally misrepresented so as to be easier to contradict.
- Oversimplifying or overcomplicating
- Taking too literally
- Taking out of context
- Changing the meaning of words or phrases half way through an argument:
- "All men are created equal, but Samantha is a woman so she is not equal."
- Assuming your conclusion:
- "You better believe in UFOs or the aliens will come and punish you."
- A logical inconsistency is a contradiction.
Inconsistency don't just happen to be wrong, they logically must be wrong.
- "What happens when an irresistible force meets an immovable object?"
Picking Apart Your Opponent(top)
- In simplest form, they reduce to "A and not A."
- Hidden assumptions
- Not all of the premises used to support a claim are stated outright.
Some assumptions can be safely left hidden.
- We may disagree with a conclusion because we disagree some of the premises that are not stated.
- These are like hidden assumptions, but they are personal feelings rather than facts.
- Not everyone uses words in the same way. Try to pin down the precise meaning of key words.
- These can be very tricky. A person may make a particular argument because they have something at stake. But, an ulterior motive does not necessarily invalidate an argument.
7 Questions to help you analyze an argument:
Is there any inconsistency?
- What is the claim and what are the supporting reasons?
- Are the reasons acceptable?
- Are the reasons relevant?
- Are there any questionable hidden assumptions?
- Are the meanings of all the words and phrases clear and consistent?
- Are there good arguments against the conclusion which have been left out?
- Much of this information is taken from the following book:
- Cannavo, S. (1998) Think to win: The power of logic in everyday life. Amherst, NY: Prometheus Books
ANTHONY G BENOIT