Friday, May 22, 2009

Book Review: Informal Logic by Douglas Walton

Informal Logic: A Pragmatic Approach (2nd Edition) by Douglas Walton is a logic book that offers the student an understanding of practical logic in dialogue and a deeper grasp of the common logical fallacies.

Walton’s book takes the angle what is called logical pragmatics. Logical semantics has to do with propositions that make up an argument. Logical pragmatics has to do with the use of these propositions to carry out a goal in a context of dialogue. As the author puts it, “logical pragmatics is a practical discipline, and applied art.” The idea here is not the focus so much on the formal aspects of logic, but logic in dialogue, discussion, and dispute.

The author places good emphasis on developing the student’s discernment of context in dialogue, as the goals and venue of the interaction play a crucial role in the ways arguments should be treated and evaluated. Walton points out: “In practical logic – often called informal logic – each particular argument must be studied on its own merits.” This means that additional attention must be given to personal dynamics and the nuances of language and its intended use.

One point that stands out in this book is that the logical fallacies are not treated simplistically: “The logical fallacies are more complex and deserving of much fuller analyses than the traditional textbook treatments have suggested.” Walton says that the old approach was to simply assign a label to the fallacy and immediately declare it fallacious. However, he suggests that each argument must be evaluated not merely in relation to the form of the argument, but also in relation to the dialogue in which it is embedded.

Walton refers to the principle of charity in dialogue. When arguments or meanings are not clearly communicated, charity should be involved in order to given the other person the benefit of the doubt until clarity can be achieved. The idea here is not jumping to conclusions too soon.

This theme of careful discernment is emphasized throughout the book’s very thorough chapters. The informal fallacies are treated in depth, with so many of their possible nuances.

Many times what looks like a fallacy is not necessarily the case. For most of the fallacies, Walton demonstrates instances where one could be quick to cry foul; however, he shows again that context, intent, and other information can tip the scales. In regard to appeals to authority, for instance: “Appeals to authority are not intrinsically fallacious, even if they can be erroneous in some cases, when misinterpreted, taken too seriously, or taken uncritically.”

Walton also describes that a number of factors must come into play for certain arguments to become fallacious. In the case of the ad hominem: “Not only does there have to be a personal attack made by one party against another, but the personal attack has to be put forward by the first party in such a way that it is meant to refute some argument previously put forward by the second party.” The reader will come away from this book being careful not to be too quick to shout “fallacy” without looking at both sides of the argument carefully.

In sum, Informal Logic is a very useful book. It brings much needed clarity and sharpness to the practical use of logical thinking in dialogue. It emphasizes careful thinking, discernment, and charity. This text can be highly recommended as a deeper treatment of the informal fallacies and a good bridge between the subjects of formal logic and critical thinking.


  1. Luke May 22, 2009

    What’s the role of truth in logical pragmatics?

  2. Brian May 22, 2009

    I am not completely clear on what you mean by the question, but a bit of an excert from the book can be found from this link which might shed some light on it.