Logic

Conditional proof is a method for proving a conditional by assuming its antecedent and deriving its consequent. Read this post or watch the video to learn how it’s done.

This post and video go over the solutions to the proofs assigned as homework in the Proofs with the Rules of Inference post and video.

This post and video begin to explain how to do proofs in symbolic logic using the rules of inference. At the end, it includes some proofs to try on your own.

This post and the video inside introduce material equivalence, which is the property of having the same truth value, in symbolic logic, as well as the rules of replacement, which let you replace some logical expressions with materially equivalent logical expressions.

Here is text and video introducing two rules of inference involving dilemmas: contructive dilemma and destructive dilemma.

Here is a video I made explaining material conditionals in symbolic logic, including three rules of inference that use them: modus ponens, modus tollens, and hypothetical syllogism. There is also a short written synopsis.

This post, and the video inside, introduce conjunctions (and-statements) and disjunctions (or-statements) in symbolic logic, along with rules of inference that use them, namely the rules of conjunction, simplification, disjunctive syllogism, and addition.