- Critical Thinking Web
"Over 100 free online tutorials on critical thinking, logic, scientific reasoning, creativity, and other aspects of thinking skills."
- IDEA Debate Database
"Arguments for and against hundreds of debating Topics, written by expert debaters, judges and coaches. Also included are background summaries, links to websites of interest and recommended books, example motions and user comments."
- Debate Central
From the World Debate Institute site at the University of Vermont, tons of information about formal debating skills and procedures.
- The Fallacy Files
Logical fallacies - what they are and how to recognize them.
- forall x
"An open access introductory textbook in formal logic."
- Guide to Parliamentary Debate
From the American Parliamentary Debate Association.
- How to Debate Effectively and Rationally
Although focused on debating political issues, the advice on this
site is applicable to debates in general.
- Introduction to Logic
Interactive introduction to logic and reasoning.
- A List of Fallacious Arguments
Describes several common fallacious arguments. Here you can learn to avoid using these false arguments yourself and to recognize when your opponant is using them.
- Mission: Critical
"The goal of Mission: Critical is to create a "virtual lab," capable of familiarizing users with the basic concepts of critical thinking in a self-paced, interactive environment."
- Online Debating Tutorial
Short introduction to debating structure and technique.
- SS Critical Thinking
Nice review of how critical thinking can be applied to reading and understanding texts.
