Did you know you can spot certain fallacies by drawing pictures? Overlapping circles, called Venn Diagrams, illustrate statements about categories (like “All cats are mammals” or “Some cats are tigers), which form the basis of categorical arguments. Here’s how to spot flawed categorical arguments...

Truth tables are tools to help you spot invalid arguments without having to know the name of a single formal fallacy, and without having to know if the statements in an argument are true! Here’s a crash introduction to how to create and interpret a truth table.

Truth tables are tools to help you spot invalid arguments without having to know the name of a single formal fallacy, and without having to know if the statements in an argument are true! Let’s walk through an example of drawing a truth table for a more complicated argument.

Here’s a shortcut to test arguments’ formal validity without drawing truth tables, just by showing if an argument’s conclusion can be false while its premises are true. Let’s see how to do this with the following argument: “If molecules-to-man evolution is true, then we can observe it directly or...