Arguments

• An attempt to justify a conclusion by rational means
• Set of statements consisting of:
  • One or more premises (supporting statements)
  • A conclusion (statement in need of support)
• A bad argument can have a true conclusion
• "Is this a good argument?" !== "Do you agree with the conclusion?"

Forms of Arguments

• Deductive arguments
• Non-deductive arguments
  • Tries to provide probable support for its conclusion
    • A conclusion should seem more likely to be true
    • Not definitive truth
  • A non-deductive argument providing probable support is strong
    • Strength comes in degrees
  • A strong argument with true premises is cogent
    • Cogency runs parallel to soundness
    • Cogent arguments can have false conclusions
  • Types
    • Inductive arguments
    • Abductive arguments
    • Analogical arguments
• Ontological arguments

Reconstructing Arguments

• Piece together an argument from a passage of text
• There may be missing pieces
  • Hidden premises or conclusions
  • Can happen due to various reasons:
    • Lazy author
    • Think premise(s) are obvious
• Look for a conclusion indicator (eg. so)
• How to find missing premises
  • Search for credible premise that would make argument valid (or as strong as possible)
  • Choose premise that is:
    • Most plausible
    • Fits best with author's intent
    • Principle of Clarity
      • Always attribute the strongest possible interpretation of an author's position consistent with the text

Evaluating Arguments

• Think about two questions:
  • Are the premises of this argument true?
  • Assuming the premises are true, to what extend do they support the conclusion?
• Look out for faulty reasoning
  • A fallacy
  • Error in reasoning that commonly persuades people

Philosophy