Reasoning I

1
Reasoning I

• Types of Reasoning and
• Logical Fallacies

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Why is reasoning important?

• Answer this question on a scrap sheet of paper.

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Why is reasoning important?

• Bricks Cement Building
• Evidence Reasoning Arguments
• Establishing your problem as real and your
  solution as practical requires the use of
  arguments.
• You are already making arguments, this class will
  help you make sense of
• Identify arguments.
• Evaluate arguments.

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What is reasoning?

• Reasoning is the process of drawing conclusions
  based on evidence.

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Reason

• Types of Reasoning
• Logical Fallacies

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Types of Reasoning

• Specific Instance. Use specific evidence to make
  a general claim.
• General Principle. Use general claims to make a
  specific one.
• Causal Reasoning. A cause results in an effect.
• Analogy. Two things are similar in nature.

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Specific Instance.

• My mom, sister, and wife are all bad drivers.
  Therefore, all women are bad drivers.
• Traffic in Virginia Beach, Norfolk, and Hampton
  is problematic. Therefore the Commonwealth of
  Virginia has a traffic problem.
• Use qualified conclusions. Avoid "hasty
  generalizations." (Problem, Solution)

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General Principle.

• U.S. Constitution guarantees all U.S. citizens
  the right to vote (major premise).
  Women are U.S. citizens (minor premise).
  Therefore, women have the right to vote
  (conclusion).
• Carbohydrates are bad for our health. Beer
  is high in carbohydrates. Therefore,
  beer is bad for your health.
• Are your premises valid? Does your conclusion
  follow? (Problem, Solution)

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Causal Reasoning.

• Radiation causes hair to fall out.
• People die from HIV/AIDS.
• Does the effect follow the cause? Is the cause a
  real cause? Avoid "False cause and
  "Simple-Complex Cause."

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Analogy.

• If you are good at racquetball, then you will be
  good at Ping-Pong.
• If you are good at spades, then you will be good
  at hearts.
• If universal health care works in Canada, then it
  will work in Kenya.
• Avoid "Invalid Analogy."

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Types of Reasoning

• Compulsory arbitration of labor disputes failed
  to work in Kansas in the early 1920's. Therefore,
  it would fail to work if the Federal Government
  were to try it.
• Since World War II juvenile delinquency has been
  increasing rapidly. During the same period the
  sale of comic books has increased equally
  rapidly. Therefore, the increase in juvenile
  delinquency results from comic books.
• Alcoholism is a dreaded disease drinking is the
  cause of alcoholism therefore, drinking leads to
  this dreaded disease.
• Pollution of our rivers is a serious problem in
  the United States. Studies by the Department of
  the Interior reveal that the Hudson, the Potomac,
  the Ohio, and the Mississippi are particularly
  bad.

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Types of Reasoning

• Compulsory arbitration of labor disputes failed
  to work in Kansas in the early 1920's. Therefore,
  it would fail to work if the Federal Government
  were to try it. (Analogy)
• Since World War II juvenile delinquency has been
  increasing rapidly. During the same period the
  sale of comic books has increased equally
  rapidly. Therefore, the increase in juvenile
  delinquency results from comic books. (Causal)
• Alcoholism is a dreaded disease drinking is the
  cause of alcoholism therefore, drinking leads to
  this dreaded disease. (General Principle)
• Pollution of our rivers is a serious problem in
  the United States. Studies by the Department of
  the Interior reveal that the Hudson, the Potomac,
  the Ohio, and the Mississippi are particularly
  bad. (Specific Instances)

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Types of Reasoning

• Compulsory arbitration of labor disputes failed
  to work in Kansas in the early 1920's. Therefore,
  it would fail to work if the Federal Government
  were to try it. (Analogy Invalid Analogy)
• Since World War II juvenile delinquency has been
  increasing rapidly. During the same period the
  sale of comic books has increased equally
  rapidly. Therefore, the increase in juvenile
  delinquency results from comic books. (Causal
  Simple-Complex Cause)
• Alcoholism is a dreaded disease drinking is the
  cause of alcoholism therefore, drinking leads to
  this dreaded disease. (General Principle False
  Minor Premise)
• Pollution of our rivers is a serious problem in
  the United States. Studies by the Department of
  the Interior reveal that the Hudson, the Potomac,
  the Ohio, and the Mississippi are particularly
  bad. (Specific Instances Hasty Generalization)

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Logical Fallacies

• Ad hominem. A speaker attacks a person rather
  than her/his argument.
• Red herring. A speaker introduces irrelevant
  information that distracts from issue.
• Bandwagon. A speaker implies or states that a
  conclusion is correct because a group believes it
  is true.
• Either-Or. A speaker claims that only two options
  are available when other, in fact, are possible.
• Slippery Slope. A speaker indicates that one step
  will inevitably lead to further steps.

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Ad hominem

• Bush wants to open up oil drilling in our
  National Parks, because he was put into office,
  in part, with financial support of oil companies.
• Of course Ted Kennedy is making that argument for
  domestic policy, he is a New England democrat.

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Red herring.

• How can we worry about the few cases of AIDS in
  our community of 50,000 when there are thousands
  of children dying of AIDS and AIDS related
  illness in other countries?
• Admittedly, men have and will abuse their wives.
  But what about the increase in men who are
  battered by their wives and girlfriends.
  Statistics show that, since 1995, the number of
  these reported cases has more than doubled.
  Because appropriate masculine response to abuse
  is unclear in our culture, we should be working
  towards assisting men, not merely more money for
  women.

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Bandwagon.

• Other forward thinking communities across the
  United States have already instituted a ban on
  smoking in public restaurants. Let's not lag
  behind the wave of progress.
• Officer, how can you pull me over for speeding 15
  miles over the speed limit, when the flow of
  traffic was clearly moving at 25 miles over.

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Either-Or.

• Either we increase funding to our before and
  after school tutoring or out students will
  continue to fail on their achievement tests.
• If we don't increase the size our hospital,
  patients who need our help will be turned out on
  the streets.

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Slippery Slope.

• If we don't address traffic problems now, we will
  soon find ourselves plagued with the traffic
  problems of a larger city. Our streets will be
  clogged and noisy. We will have to build more
  roadways, which will ruin the image of our city.
  We will go from a choice city to just another
  ugly, overcrowded example of urban sprawl.
• We have to stop the tuition increase! The next
  thing you know, they'll be charging 40,000 a
  semester!

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Logical Fallacies

• I dont see any reason to wear a helmet when I
  ride a bike. Everyone bikes without a helmet.
• I think it is ridiculous to worry about
  protecting Americas national park against
  pollution and overuse when innocent people are
  being endangered by terrorists.
• If we allow the school board to spend money
  remodeling the gymnasium, next they will want to
  build a new school and give teachers a huge
  raise. Taxes will soar so high that businesses
  will leave and there will be no jobs for anyone
  in this town.
• I cant support Representative Freys proposal
  for campaign finance reform. After all, he was
  kicked out of law school for cheating on an exam.
• Our school must raise tuition, or cut back on
  library services.

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Logical Fallacies

• I dont see any reason to wear a helmet when I
  ride a bike. Everyone bikes without a helmet.
  (Bandwagon)
• I think it is ridiculous to worry about
  protecting Americas national park against
  pollution and overuse when innocent people are
  being endangered by terrorists. (Red Herring)
• If we allow the school board to spend money
  remodeling the gymnasium, next they will want to
  build a new school and give teachers a huge
  raise. Taxes will soar so high that businesses
  will leave and there will be no jobs for anyone
  in this town. (Slippery Slope)
• I cant support Representative Freys proposal
  for campaign finance reform. After all, he was
  kicked out of law school for cheating on an exam.
  (Ad Hominem)
• Our school must raise tuition, or cut back on
  library services. (Either-or)