Practical Reasoning
Douglas N. Walton
Is a goal driven, knowledge based, action guiding species of reasoning that meshes together goals with possible alternative actions that are means to carry out those goals, in relation to an agent’s given situation as he or she sees it, and concludes in a proposition that recommends a prudent course of action. Practical reasoning is a defeasible kind of argumentation, in that it is tentative in nature – subject to revision as new information concerning the agent’s changing circumstances comes to be known. Practical reasoning is crucial to the underlying framework of virtue ethics, where it defines the right personal characteristics needed to under take a prudent course of action in relation to an agent’s ethical goals as applied to a given situation (see virtue ethics).
An example would be the case of a manufacturer who wants to market a drug, but knows that satisfying the regulatory safety requirements will involve costly testing of the drug. To arrive at a prudent line of action, the manufacturer might take a close look at how the drug would be tested, including such factors as who would carry out the tests, how much this would cost, what options are available, how long it would take, and so forth. They would then put this information together with their goals in manufacturing, making a judgment of how much of a priority manufacturing this particular drug should be for them. Their deliberations on the question should take the form of practical reasoning that meshes their general goals as a company with specific information about this drug, and the means necessary to manufacture it under current, or reasonably predictable, circumstances.
Practical reasoning, in its simplest form (Walton, 1990), is an inference with a goal premise and a means premise: ‘‘G is my goal ; carrying out action A is the means, in this situation, to realize G; therefore, I should carry out A.’’ Al though this simple structure gives the reader a basic idea of how practical reasoning works, other factors need to be taken into account. In Walton (1991: 109), these other factors are ex pressed in the form of critical questions that should be asked in a given case. One factor is that there may be more than one means available, so that the various possible alternative lines of action may need to be compared. Another factor is that the agent may have multiple goals, so that it may be necessary to decide which goals have priority over others. There may even be practical conflicts (i.e. conflicts between carrying out one goal and carrying out another), where the line of action required to carry out one goal would interfere with, or cancel out, the line of action required to carry out the other. Another factor is that of side effects. The practical reasoner needs to ask critical questions about the likely con sequences, both positive and negative from the point of view of her goals, of carrying out a contemplated action. A final factor is that the contemplated action may require prior actions to carry it out. Often, a number of preparatory actions are needed. Thus, in complex practical reasoning, it is not just a single action in isolation that needs to be considered. Typically, it is a connected sequence of actions that leads toward the goal.
Bibliography
Walton, D. N. (1990). Practical Reasoning: Goal Driven, Knowledge Based, Action Guiding Argumentation. Savage, MD: Rowman and Littlefield.
Walton, D. N. (1991). Begging the Question: Circular Reasoning as a Tactic of Argumentation. New York: Greenwood Press.