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Argumentative Writing. Reasoning Critically. Inductive and Deductive Reasoning. Inductive & Deductive Reasoning.
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Reasoning Critically Inductive and Deductive Reasoning
Inductive & Deductive Reasoning • To think, read and write critically, you need to distinguish sound reasoning from faulty reasoning. Induction and deduction are the two basic reasoning processes. They are natural thought patterns people use everyday to help them think through ideas and make decisions.
Inductive Reasoning • Inductive Reasoning moves from particular facts or instances to general principles. Suppose you go to the Registry of Motor Vehicles to renew your driver’ license and have to stand in line for two hours. A few months later you return to get new license plates and once again you have to stand in line for two hours. You mention your annoyance to a couple of friends who say they had exactly the same experience. You conclude that the registry is inefficient and indifferent to the needs of its patrons. You’ve arrived at this conclusion by
Deductive Reasoning • Deductive reasoning is the process of reasoning from general claims to a specific instance. Suppose you know that students who don’t study for Professor Sanchez’s history tests tend to do poorly. If your friend tells you she didn’t study, you can make a reasonable conclusion about her grade. Your reasoning may look like this:
Premise 1: Students who don’t study do poorly on Professor Sanchez’s exams. • Premise 2: My friend didn’t study. • Conclusion: Therefore, my friend probably did poorly on the exam. • Deductive arguments have three parts: two premises and a conclusion. This three part structure is known as a syllogism.
The first and second premises of a deductive argument may be statements of fact or assumptions. They lead to a conclusion, which is the point at which you want to think as precisely as possible because you’re into the realm of validity. • A deductive argument is valid when the conclusion logically follows from the premises; a deductive argument is invalid when the conclusion doesn’t logically follow from the premises. For example:
Valid Deductive Argument • P 1: When it snows, the streets get wet. • P 2: It is snowing. • Conc: Therefore, the streets are getting wet. Invalid Deductive Argument • P 1: When it snows, the streets get wet. • P 2: The streets are getting wet. • Conc: Therefore, it is snowing.
Here’s the problem with the invalid deductive argument: It has acceptable premises because they are facts. However, the argument’s conclusion is wrong because it ignores other reasons why the streets might be wet. For eg., the street could be wet from rain, from street cleaning trucks that spray water, or from people washing their cars. Therefore, because the conclusion doesn’t follow logically from the premises, the argument is invalid.
What is a written Argument? • When you write an argument, you attempt to convince a reader to agree with you on a topic open to debate. You support your position, proposal, interpretation with evidence, reasons and examples- factual, logical data, not opinions.
How do I develop an assertion and a thesis statement for my argument? • An assertion is a statement that expresses a point of view on a debatable topic. It can be supported by evidence, reasons, and examples (including facts, statistics, names, experiences, and experts). The exact wording of the assertion rarely finds its way into the essay, but the assertion serves as a focus for your thinking. Later, it serves as the basis for developing your thesis statement.
Topic: Wild animals as domestic pets. • Assertion: People should not be allowed to won wild animals. • Assertion: People should be allowed to own wild animals.
Topic: Private ownership of wild animals. • My position: I think private ownership of wild animals should not be allowed. • Thesis: It is bad for private citizens to own wild animals as pets. (The word bad is vague and the writer doesn’t address how to stop private ownership of animals.) • Thesis: To eliminate what few people realize are increasingly dangerous situations for people and animals alike, ownership of wild animals as pets by ordinary people needs to be made completely illegal. (it’s better but it suffers from lack of conciseness and from the unnecessary passive construction ‘needs to be made’.) • Thesis: To eliminate dangerous situations for both people and animals, policymakers need to ban private ownership of wild animals as pets.
Activity 1 Choose a topic from the list below and develop an assertion and a thesis statement. You may choose any defensible position. For example: • Topic: Book censorship in high schools • Assertion: Books should not be censored in high school. • Thesis statement: When books are taken off high school library shelves or are dropped from high school curricula, students are denied an open exchange of ideas. • Watching television many hours each day • The commercialization of holidays • Taking body-building supplements • Grading on a pass/ fall system
Elements of an Argument • The issue • The claim • The evidence • The opposing claims
The issue • An issue is a matter of public concern. Gun control, abortion, affordable health care are issues. An issue can be a problem that needs a solution or a question that requires an answer. Issues are often controversial; where issues are involved, people take sides.
The Claim • A claim is either an assertion or a statement of what you believe to be true or a demand that something be done. “He injured me with his car” is an assertion. “He ought to pay my medical bills” is a demand. Both of these claims require proof if the injured person expects to convince a court that he or she was injured and should get paid. A claim is different from an issue, in that an issue is a matter of public concern or controversy, such as “gun control,” but a claim is your position on the issue, the assertion or demand you make, such as
“gun control denies citizens the right to protect themselves and ensures that only criminals will have guns.” Many statements of claim will either include words such as ought to, should, need, and must or imply the idea that something should or ought to be done.
The following is a list of claims about the issue of cheating: • The student government should establish an honour court to deal with cheating. (demand) • We should re-examine our college’s policy on cheating. (demand) • The reasons the college students cheat are more alarming than the cheating itself. (assertion) • The solution to cheating is everyone’s responsibility. (assertion)
The Evidence • Hard evidence: rational appeal • Soft evidence: emotional appeal • Hard evidence includes facts, examples, and authoritative opinion and it makes a rational appeal to readers to use their reasoning powers. A non-smoking ad on television that uses facts such as the percentage of smokers who die from heart and lung diseases is using hard evidence to get smokers to think about their chances of survival if they do not give up their habit.
Soft evidence • Soft evidence includes moral considerations, common sense observations, personal opinions and social values. It makes an emotional appeal to readers to listen to their hearts and consciences. A non-smoking ad on television that uses social values and common sense might show attractive young people making statements such as: “Even a smart guy looks dumb with a cigarette in his mouth” or “I’m not interested in kissing a woman who has smoker’s breath.”
The Opposing claims • If all you do is make a claim and support it, your argument will be one-sided and therefore unconvincing. A persuasive argument will acknowledge differing opinions and answer opposing claims.
