Natural Deduction Proofs: The Basics 

An easy intro to natural deduction proofs. Inference rules like simplification and modus ponens are explained along the way. Using rules of inference to prove a conclusion in step-by-step fashion is called natural deduction-a proof-and is part of any introductory logic course. Some philosophy or critical thinking courses may also involve simple logic proofs.
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Further Reading
Paul Herrick, Introduction to Philosophy, Chapter 18, "Modern Truth-Functional Natural Deduction, Part 1: The First Four Rules" (Recommended companion textbook for this channel.)
Internet Encyclopedia of Philosophy, "Natural Deduction"
www.iep.utm.edu/nat-ded/
Mental Floss, "14 Darling Facts About Ladybugs"
www.mentalfloss.com/article/8...