Logical Fallacies

Logical Fallacies

1. illogical statements that may sound reasonable or true but are actually deceptive and dishonest

2. Hasty or Sweeping Generalization

   • occurs when a conclusion is reached on the basis of too little evidence Sometimes called jumping to a conclusion
   • “Because our son benefitted from home schooling, every child should be educated in this way.”
     • Perhaps other children would benefit from home schooling, and perhaps not, but no conclusion about children in general can be reached on the basis of just one child’s experience.

3. False Dilemma:

   • occurs when writers suggest that only two alternatives exist even though there may be others
   • “We must choose between life and death, between intervention and genocide. No one can be neutral on this issue.”
     • Oversimplifies the issue and forces people to choose between extremes instead of exploring more moderate positions

4. Appeal to Doubtful Authority

   • often people will attempt to strengthen an argument with references to experts or famous people. These appeals are valid when the person referred to is an expert in the area being discussed. They are not valid, however, when the individuals cited have no expertise on the issue.
   • “According to Diane Sawyer, interest rates will remain low during the next fiscal year.”
     • Although Diane Sawyer is a respected journalist, she is not an expert in business or finance. Therefore, her pronouncements about interest rates are no more than a personal opinion or, at best, an educated guess.

5. Post Hoc, Ergo Propter Hoc

   • (After This, Therefore Because of This): assumes that because two events occur close together in time, the first must be the cause of the second Known as post hoc reasoning
   • “Every time a Republican is elected president, a recession follows. If we want to avoid another recession, we should elect a Democrat.”
     • Even if it were true that recessions always occur during the tenure of Republican presidents, no causal connection has been established.