Chapter 4: Inductive Arguments
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Transcript of Chapter 4: Inductive Arguments
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Chapter 4: Inductive Arguments
This chapter will cover
• The use of statistical evidence in arguments
• The reporting of statistical data
• The use of causal generalizations
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Inductive Reasoning
Inductive Reasoning
• Evidence offers strong support ‘beyond a reasonable doubt’
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Inductive Reasoning
Likely to be true
• Evidence is strong support but it is not 100% certain.
• Evidence gives weight but not certainty.
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Inductive Reasoning
Using evidence
• The strength of a conclusion is based on the quality of evidence used to support the conclusion.
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Reasoning
Inductive
• Cycle - bump- misfire• Cycle - bump - misfire• Cycle - smooth road
- it does not misfire• Cycle – 3rd bump-misfire
Conclusion?
Deductive
• The horn is powered exclusively by electricity from the battery.
• The battery is dead.
Conclusion?
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Inductive Reasoning
Induction
• Drawing generalizations from known facts – research, statistical evidence
• Finding truth by making observations
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Statistical Evidence
Why we use statistics
• Control over the unknown
• To make predictions and decisions
• To anticipate accurate information
• Connect patterns in our lives
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Statistical Evidence
Statistical Evidence
Data collected by polling and research studies
Gallup poll How people voteHarris poll
Statistical generalizations
Inferences from statistical evidence
Leads to
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How Research is Done
Three questions
1. What do I want to find out? Characteristic of interest2. Whom do I want to know about? Target population3. Whom can I study to get accurate answers? Sample
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Sample
Members of the target population
• Must be large enough• Must be random• Must be representative
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Skill Analyze the quality of statistical evidence by
noting the size, representation, and randomness of the sample
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Sample
Reliability
1. Sample size 1,000 randomly selected individuals2. Representative If not it is biased3. Significant characteristics Sometimes difficult to know4. Biased questions
Loaded or leading questions
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Causal Generalizations
Reasons
• Eliminate difficulties• Prevent future problems• Human curiosity
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Hume’s Method
Hume’s Conditions1. X, the cause, preceded y, the
effect, in time
2. X and y are contiguous (in contact with one another) in time and place.
3. There is a history of (1) and (2); that is, there is a history of x preceding y and of x and y being related in time and place
Interpretation1. If one thing causes another,
the cause must come before the effect
2. The need for a relationship in time and space between cause and effect
3. Chart a tendency
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Hume’s conditions
Considerations
• “Correlation is not causation.”• A “third-variable” could be the source of the
relationship.
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Cause and Effect
Technical Causation
• Necessary condition- condition must be present if the effect is present
• Sufficient condition- if condition is present, effect will definitely occur
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Stop and Think It has been said that holding elections is a necessary
but not a sufficient condition for establishing a democracy. What do you believe would be other necessary factors that would become sufficient for establishing a democratic government?
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Mill’s Analysis
John Stuart Mill
• Canons • Foundational to controlled studies
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Mill’s Analysis
Method of Agreement
• X is the only factor always present when Y occurs:Therefore, X causes Y
Method of Difference
The only difference between (Y) happening or not is whether one element (X ) is present
If:• X is present then Y occurs• X is not present then Y does not
occur
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Chapter 4: Inductive Arguments
Checkup
• Uses of statistical generalizations• Multiple causes of a problem• Problems with statistical evidence• Sample, target audience, characteristic of
interest• Cause and effect- Hume and Mill’s