Proving De Morgan’s with Indirect Proof
In this last lesson on sentential logic, though not on symbolic logic, we go over solutions to proofs for De Morgan’s theorems.
What is a Cult?
A detailed examination of characteristics that distinguish a cult from other religious groups.
Introducing Indirect Proof
Indirect proof, or reductio ad absurdum, is a method for proving something by showing that the assumption of its opposite would entail a contradiction.
Atheist or Agnostic?
Neil deGrasse Tyson has identified himself as an agnostic instead of an atheist. What should we make of this? And what is the distinction?
Proving Distribution with Conditional Proof
This symbolic logic lesson goes over proofs of both forms of the rule of Distribution, which is one of the rules of replacement.
Proving Disjunctions with Conditional Proof
This lesson in symbolic logic focuses on how to use conditional proof to prove disjunctions.
Nesting Conditional Proofs
Here we take a closer look at how to nest conditional proofs, illustrating it with a proof of the rule of exportation.
Rules of Inference for Biconditionals
To keep the lines in our proofs shorter, this introduces rules of inference for introducing or eliminating biconditionals.
Silly Syllogisms
A Syllogisms tutor I originally wrote in 1990.
Who Thinks for You? Awake! Article on Propaganda from 1947
In 1947, the Jehovah’s Witness magazine Awake! published a very informative article on the tricks propagandists use to manipulate people’s thoughts and opinions.