An Introduction to Deductive Arguments

Unit #4 Summary

In this unit we focused on deductive arguments.  As we have seen, deductive arguments are indefeasible and have maximal logical strength due to their form.  Although there are many argumentative forms, we specifically identified four especially common ones.  We also looked at two forms people commonly confuse for deductive forms.  Because strict conditionals are such an important part of many deductive arguments, we talked through what a strict conditional is really saying, and identified a variety of different ways we express conditionals.  This led, finally, to a consideration of the many ways that deductive arguments, themselves, can be expressed.

Key Terms

  • Deductive Arguments
  • Defeasible Arguments
  • Indefeasible Arguments
  • Argument Form
  • Strict Conditionals
  • Modus Ponens (MP)
  • Modus Tollens (MT)
  • Hypothetical Syllogism (HS)
  • Disjunctive Syllogism (DS)
  • Denying the Antecedent (DA)
  • Affirming the Consequent (AC)
  • Conditional Statement
  • Sufficiency Relation
  • Necessity Relation
  • Contrapositive

Further Reading

People have been studying deductive arguments for over 2000 years going back at least to the work of Aristotle in the 4th century BCE.  The study of deductive arguments is known as deductive or formal logic and there are many solid introductory books on the topic.  Two in particular that stand out are A Concise Introduction to Logic by Patrick Hurley and The Power of Logic by Frances and Daniel Howard-Snyder.



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Arguments in Context by Thaddeus Robinson is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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