Introduction to Symbolic & Philosophical Logic

Although almost every activity human beings engage in requires some degree of reasoning, we're often sloppy at it, we seldom (if ever!) think about the thinking process itself, and we are really good at tying ourselves into conceptual knots and logical contradictions. For more than two thousand years, however, philosophers have been hard at work trying to understand, organize, classify and perfect the reasoning process, searching for and discovering the rules and principles of logical necessity, devising methods for ascertaining the validity of logical inferences, and testing the very limits of reasoning.

The following Prezi is a compilation of a number of lectures by philosopher Mark Thorsby. These lectures provide a great introduction to deductive symbolic reasoning in:

1. Categorical logic (syllogisms and sorites), 
2. Propositional logic (and natural deduction), and 
3. Predicate (or 1st-order) logic.

If you've ever been curious about symbolic logic, but felt intimidated by the scariness of its symbols and notation, fear no more: these lectures are nicely organized and highly accessible, no matter your academic background or level of education.

These ideas may seem abstract and academic, and there's something to that charge, but they are also the ideas that make the modern world possible: our scientific knowledge, the technology on which our very survival depends, the political and economic systems through which we organize our social lives, our ability to reason about ethical questions, our very ability to communicate our thoughts and feelings to each other, and many other important domains, all depend on our ability to think clearly and reason properly...