Argumentation and Fallacies

Types of Reasoning and Argumentation

Students should become familiar with the four basic types of reasoning that can be used to construct a persuasive argument. Instructors should attempt to work these forms of reasoning into the lessons of the course about quantitative reasoning.

• Inductive Reasoning. From a set of “particular” instances, we can derive a more general or universal claim.
• Deductive Reasoning. From one universal “truth”, specific claims are derived.
• Analogical Reasoning. From one particular instance to another, we can suggest that enough factors are similar to warrant a comparison.
• Causal Reasoning. If x causes y, then it makes sense that removing “x” should stop “y.”

Examples, case studies, in-class exercises and so forth can be used to illustrate these concepts.

Fallacies

Fallacies are flawed or intentionally deceptive arguments. They are either the result of poor reasoning or an intentional attempt to manipulate the audience. In either case, students should be able to identify the more common fallacies, and obviously should never use one in a speech.

Some of the common fallacies to discuss, in no particular order, are:

• Ad populum (appeal to popularity)
• Ad hominem (personal attack)
• Strawman argument (knocking down a fake position)
• Red Herring (irrelevant distraction)
• Appeal to False Authority
• False dichotomy; “Either/Or” fallacy
• Appeals to tradition (“we’ve always done that, so we can’t change it now”)
• Post hoc ergo propter hoc; “After this, therefore because of this” reasoning
• “Correlation is not Causation”
• Single Cause (most problems have multiple causes, so suggesting there is only one is weak reasoning)
• Non-sequitur (the conclusion doesn’t follow from the premises)
• Circular Reasoning (“it’s true because it’s true)
• Weak Analogy (“comparing apples to oranges”)
• Myth of the Mean (misleading averages as evidence)

Obviously, add any you think are relevant to the course!