Philosophy 2, Introduction to Logic, 3 units

**Catalog Description**

This course is an introduction to the problems and techniques of traditional and modern logic comprising both deductive and inductive inference. The student will learn to distinguish arguments from non-arguments, to identify and avoid common fallacies in reasoning, to test for validity both truth functional arguments and categorical syllogisms, to construct simple formal proofs of validity in truth-functional logic, and to understand the nature of inductive reasoning and its relationship to the sciences.

**Prerequisite**

None

**Text **

No department requirement. This has traditionally been a standard college class. Many texts cover this material: Copi, Hurley, Manicas and Kruger, Barker, Johnson, etc.

**Course Objectives**

- The student should be able confidently to assess, for a wide range of arguments, whether or not, and to what extent, conclusions follow from, or are supported by, premises.
- Students should be able to apply techniques of logical analysis to their own thinking, so that their arguments become more precise, powerful, and persuasive.
- The student should be able to demonstrate proficiency in the formal techniques for establishing the validity of deductive arguments. These techniques include Venn diagrams and syllogistic rules for categorical logic, and truth tables, simple natural deduction, and, optionally, truth trees for truth-functional logic.
- The student should be able to diagnose common informal fallacies, identify vagueness, and clarify meanings.
- The student should be able to distinguish scientific reasoning from other types of reasoning, and be able to explicate and apply the techniques of scientific reasoning.

**Course Content**

I. WHAT IS LOGIC? 1 week The concept of an argument Distinguishing arguments from non-arguments Complex arguments Inductive vs deductive logic Validity and soundness Formal systems: vocabulary, grammar, semantics, syntax Deductive logic as a formal system. II. MEANING AND DEFINITION 2 weeks Functions of language and grammatical forms: no 1-to-1 correspondence Emotive language Meaningfulness and nonsense - the logical empiricist criterion Recognizing and avoiding ambiguity Kinds of definition Intension and extension Verbal disputes versus genuine disagreement III. INFORMAL FALLACIES 3 weeks The general distinction between formal and informal fallacies Specific informal fallacies. Different textbooks group the fallacies differently. At least the following should be covered: equivocation, composition, division, begging the question, accident, slippery slope, irrelevant emotional appeals (appeals to pity, force, vanity, mob, patriotism, etc.), ad hominem, questionable authority, false dilemma, impromptu definition, loaded question, inconsistency. IV. CATEGORICAL LOGIC 4 weeks Categorical propositions Immediate inferences Syllogisms and techniques for determining validity of syllogisms (Venn diagrams and/or rules) Translating arguments in ordinary language to syllogisms V. LOGIC OF TRUTH FUNCTIONS 5 weeks Ordinary sentential connectives and truth-functional sentential connectives Truth tables Using truth tables to determine validity Logical form and substitution instances Common valid argument forms: modus ponens, modus tollens, disjunctive syllogism, chain argument (hypothetical syllogism), dilemmas, etc. Logical equivalence; proving logical equivalence using truth tables Common logical equivalences: DeMorgan's laws, double negation, commutative law, etc. Using common valid argument forms and common logical equivalences to construct formal proofs of validity of truth-functional arguments (Optional) The truth tree method Truth tables and computers VI. INDUCTIVE LOGIC 2 weeks Inductive fallacies, e.g., hasty generalization The logic of confirmation: Mill's methods Causal fallacies: post hoc, correlation vs causation Arguments from analogy Fallacious or questionable analogies

**General Requirements**

Completion of required reading and final exam. Other requirements are determined by instructor; these may include homework, quizzes, other exams,
class participation, class attendance, etc.

**Evaluation**

Generally, evaluation is based primarily on written examinations. The exams are primarily "objective" skill demonstration. Students generally do not write essays in this class.

**Suggested Instructional Methods and Materials**

Primarily lecture and discussion. Since racist and sexist attitudes are often the result of the application of bad reasoning techniques, racist and sexist arguments are recommended for use as examples of bad argumentation, where appropriate. Computer-aided instructional materials are available. Guest speakers, class debates, etc., may be used as appropriate according to the preference of the individual instructor.

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Page last modified: April 30, 1999