9: More Fallacies in Debating

Special Pleading & Slippery Slope

Informal Fallacies

Key Terms

Modus Ponens
Modus Tollens
Disjunctive Syllogism
Reduction Fallacy
Post Hoc Ergo Propter Hoc
Texas Sharpshooter Fallacy
False Dilemma
Straw Man
Special Pleading
Slippery Slope

  • Not logical
  • Pseudo-reasoning (false reasoning)
  • Unsound arguments

Fallacies in Debating

  • Deny, confuse, or falsify an argument most often in a debate
  • Six types:
    • False Dilemma
    • Straw Man
    • Special Pleading
    • Slippery Slope
    • Meaningless Jargon
    • Weasel Words

Special Pleading

  • Argument that premise is beyond criticism
  • or, Premise transcends our understanding


  • Apollo’s chariot carries the sun across the sky. This has been common knowledge for centuries. No mortal has the ability to understand why or how this occurs. It just is.


  • Reasonable claims must be justifiable. Anyone can make any sort of claim (e.g. Apollo's chariot carries the sun), but if he or she wants to present a valid argument then the claim must fall within the confines of evidence and reason. Otherwise, it is simply a personal belief and not falsifiable knowledge.

Slippery Slope

  • Asserts an event will have a future negative effect
  • Effects are extreme in nature


  • If we legalize marijuana, millions of people will become addicted to heroin.
  • If You Give a Mouse a Cookie children’s book series by Laura Joffe Numeroff
  • Humorous approach from Robot Chicken Clip


  • Conclusions drawn from invalid premise or conclusions require a stretch in logic
  • Slippery Slope is impossible to disprove because it predicts the future