Friday, May 29, 2009

Logic Primer 5: Logical Fallacies

Today we will look at logical fallacies. A fallacy is simply an error in thinking. Certain errors are so common they have been classified and named. These are the sorts of fallacies we are dealing with here.

There are two primary categories of fallacies: formal and informal. Formal fallacies have to do with the logical structure of an argument. If the logical structure is incorrect, then the argument has committed a fallacy. Informal fallacies have to do with errors of thinking that happen apart from the structure of an argument. These could include such things as appeals to emotions, personal character attacks, and ambiguous language.

When it comes to informal logic, the tendency for the beginner is to gravitate immediately to the fallacies. Immediate benefit can be gained by understanding where thinking may have gone wrong. However, the student of logic is encouraged to be careful not to label every apparent fallacy they can find. This is not only in many cases impolite, it is not very productive. Recognizing fallacies is only the first step. But bringing proper thinking and clarity to an issue can be the real challange. Every case has its own particular elements, so more information is always helpful to determine the strengths and weaknesses of arguments.

Ideally, when a fallacy is recognized it can be corrected without a sort of “gotcha” attitude. The principle of charity and a gracious manner are essential in seeking common understanding, rather than simply becoming a fallacy-finder.

Because the fallacies cover such a broad range, they are beyond the scope of one post. In addition, many excellent resources can be found on the web for studying the fallacies. Although many good resources are found in print, good audio resources are few. That is why we have provided here an audio podcast adaptation of Stephen’s Guide to Logical Fallacies, one of the well-known fallacy sites on the web. Permission has been granted by logician Stephen Downes. The purpose of the podcast is to introduce and summarize the fallacies and provide examples and solutions to the errors.

You can find the Apologetics 315’s Logical Fallacies podcast on iTunes here. Or use the RSS feed found here. The Logical Fallacies 2nd Edition podcast can be found here.

Stephen’s Guide to Logical Fallacies is found here, with a nice mirror-site with additional content added by Christian philosopher J.P. Moreland at the Illogic Primer here.

The Nizkor Project 42 Fallacies is here.

Audio by Michael Ramsden on Logic and Fallacies can be found here.

Helpful Books:
Nonsense by Robert Gula
Informal Logic by Douglas Walton



  1. nbjacobson June 2, 2009

    Thanks for the link, 315. Just to clarify, the Illogic Primer at, to the increasing extent that it differs from Stephen’s Guide, is authored by yours truly. I wouldn’t want JP blamed for any of my lapses in thinking. For what its worth, JP (and Craig) have an excellent basic introduction to logic in their Philosophical Foundations for a Christian Worldview. Also, though Walton is certainly the most prolific in this area, in my research for the Primer, I consistently find that Kahane’s and Cavander’s Logic and Contemporary Rhetoric and Tindale’s Fallacies and Argument Appraisal are superb. Keep up the good work. ~ Nate

  2. Brian June 2, 2009

    Thanks for that info and feedback.

  3. Geloof en Rede online August 27, 2015

    Maybe interesting to know: William Lane Craig has a book on logic for beginners "Learning Logic".