Propositional Logic·Guided Practice·Lesson 5 of 6

Building Short Formal Proofs

Introduces the basic inference rules of propositional proof (modus ponens, modus tollens, hypothetical syllogism, disjunctive syllogism, simplification, conjunction, and addition) and teaches students to build short formal proofs step by step.

← Truth Tables, Equivalence, and Validity Propositional Logic: Form, Connectives, and Valid Inference Capstone: Symbolizing, Proving, and Refuting Propositional Arguments →

Student Pro

Unlock this lesson and the rest of the curriculum.

Free includes the entire Foundations unit plus the first lesson of every other unit. This lesson is in Propositional Logic: Form, Connectives, and Valid Inference; the rest of the unit, and every other unit, is Student Pro.

In this lesson · 7 sections · 2 worked examples · 2 practice activities

Why proofs complement truth tables
The four main inference rules
The three auxiliary rules
Proof format and justification conventions
…and 3 more

$119/year

Under $10 a month, billed annually — or $14 month-to-month.

Every lesson in all 15 units
Unlimited detailed feedback on every written response
Full spaced-repetition queue and adaptive recommendations

Unlock with Student Pro Or $14/month

14-day refund on annual. Cancel anytime. No charge until you confirm at checkout. Already have Student Pro? Sign in.

Compare all plans Teaching a class? Team plans cover every student Back to Propositional Logic: Form, Connectives, and Valid Inference Curriculum