Portland Community College | Portland, Oregon

Course Number:
PHL 221
Course Title:
Symbolic Logic
Credit Hours:
Lecture Hours:
Lecture/Lab Hours:
Lab Hours:
Special Fee:

Course Description

Introduces the concepts and techniques of modern symbolic logic for deductive inference. Develops basic propositional and predicate logic skills including: translating ordinary language into symbolic statements, using truth tables for various logical tests, applying inference rules and strategies in argument proofs, and evaluating the validity of complex deductive arguments. Requires: Basic computer skills (including the ability to use MyPCC and D2L, and perform online searches). Prerequisites: WR 115, RD 115 and MTH 20 or equivalent placement test scores. Recommended: MTH 65 or MTH 95. Audit available.

Addendum to Course Description

The course may include a summary of traditional categorical (syllogistic) logic as an historical and/or methodological introduction to modern symbolic logic. 

Intended Outcomes for the course

Upon completion of the course students should be able to:

  • Distinguish statements from other kinds of ordinary language expressions.
  • Convert an argument from its original context into standard argument form.
  • Translate ordinary English language statements and arguments into symbolic form.
  • Use formal methods of propositional and predicate logic for analyzing the logical structures of ordinary language statements, and for determining the validity of deductive arguments.
  • Construct valid arguments of their own and accurately evaluate the arguments of others.
  • Use basic logic concepts and techniques for disclosing ill-conceived ideas and irrational arguments.
  • Explain how symbolic logic can assist in eliminating the ambiguity, vagueness, and redundancy of ordinary language statements.
  • Reflect on and discuss the advantages and limits of symbolic logic in the development of strong reasoning skills.

Aspirational Goals

  • Reinforce the commitment to rational discourse and the development of strong critical thinking skills. 
  • Contribute to, and perpetuate the intellectual, artistic, and spiritual inheritance of our society. 
  • Continue studies that require advanced verbal and logical skills, as well as more specialized studies in Philosophy or any other field that requires mature critical thinking skills.

Outcome Assessment Strategies

The primary methods of this course are diligent study and reflection, frequent practice with logic exercises, and rational discourse. Assessment strategies will include some of the following:

  • Logic exercises / problems
  • Short-answer quizzes
  • Worksheet projects
  • Group discussions
  • Short essays
  • Assignment completion
  • Attendance / Engagement level

Course Content (Themes, Concepts, Issues and Skills)

Major Topics €‹

  • Arguments, Premises, and Conclusions
  • Recognizing Arguments
  • Deduction and Induction
  • Validity, Truth, Soundness, Strength, Cogency
  • Argument Forms: Proving Invalidity
  • Definitions and Their Purposes
  • Definitional Techniques
  • The Components of Categorical Propositions
  • Venn Diagrams and the Modern Square of Opposition
  • Translating Ordinary Statements into Categorical Form
  • Propositional Logic: Symbols and Translation
  • Truth Functions
  • Truth Tables for Propositions and Arguments
  • Argument Forms and Formal Fallacies
  • Argument Proofs Using Natural Deduction or Truth Tree Methods
  • Conditional and Indirect Proofs in Propositional Logic
  • Predicate Logic: Symbols and Translation
  • Using the Rules of Inference in Predicate Logic
  • Change of Quantifier Rule
  • Conditional and Indirect Proofs in Predicate Logic

Key Skills

  • Translating ordinary language into symbolic statements
  • Using truth tables for various logical tests
  • Using inference rules (natural deduction), or truth trees for evaluating the validity of complex deductive arguments