PHIL 120 Exam 3 (PHIL 120) | 2025/2026 | 100+ Logic Q&A on WFFs, Truth Tables, Validity, Equivalence

This document contains 100+ fully answered and verified questions for Exam 3 in PHIL 120 (Introduction to Logic) at the University of Illinois, prepared for the 2025/2026 academic year. It provides a comprehensive and exam-grade A+ study resource for mastering formal logic principles, symbolic translation, truth tables, and argument validity—core components of introductory logic courses in philosophy and mathematics departments. Key topics include: Truth-functional logic operations, including conjunction (·), disjunction (v), negation (~), conditional (⊃), and biconditional (≡) Translation of English statements into symbolic logic (e.g., “It will rain and we won’t go to the beach” becomes R · ~B) Identification of Well-Formed Formulas (WFFs) and recognition of invalid syntax based on structural rules Main operator detection in compound logical expressions and determining logical form Truth table construction for evaluating tautologies, contradictions, contingencies, and logical equivalence Validity and soundness of arguments using formal truth table analysis and symbolic derivation techniques Common inference rules and derivations, including Modus Ponens (MP), Modus Tollens (MT), Disjunctive Syllogism (DS), Hypothetical Syllogism (HS), and Double Negation This document is especially useful for: Undergraduate students in philosophy, mathematics, or computer science taking formal logic courses Students preparing for midterms or finals in symbolic logic or critical reasoning Pre-law or GRE test-takers seeking to build deductive reasoning and logic skills Instructors and tutors needing practice questions with solutions for class exercises or review The format is exam-aligned and concise, allowing for focused review and practice with clear, structured answers across all major types of logic exercises taught at the introductory level. Keywords: symbolic logic, truth tables, logical equivalence, WFF identification, valid arguments, Modus Ponens, Modus Tollens, logical derivation, statement logic, tautology, contradiction, PHIL 120 exam, propositional logic, inference rules, University of Illinois logic course