conclusion are related inferentially, they tend to look at the relation from the perspective of a “whole argument’’, which covers the totality of premise and conclusion in the argument. In that perspective, their interest lies primarily in the analysis of the principles or rules that constitute the validity of the relation, rather than how the relation can be constructed from scratch.
No doubt, the conventional approaches are useful for developing analytical tools and techniques that could help to distinguish correct from incorrect reasoning (Copi and Cohen 2005, p. 4), but based on my years of observation, students cannot learn how to construct logical arguments for their own research simply by learning how to analyze some given examples of logical arguments and fallacies. There is a gap between argument analysis and argument construction.
By starting from a thesis statement and then finding the premise(s) that can contribute to forming the proof of the statement, LWPC takes a construction approach towards building a logical argument. The major advantage of this approach is effectiveness.
In the conventional analysis approaches, an inference is made from premise to conclusion. But making inference in this way is boundless, simply because one can draw an infinite list of inferences based on a single premise. It is just like boarding a vehicle without knowing the destination. Going from a conclusion to premise, on the other hand, helps to draw a boundary in which the inference should be made. This is similar to how a crime investigation is conducted. Very briefly, in a typical crime investigation, the investigation will begin at the point that a crime has been committed - e.g. someone has been killed, or some bank has been robbed. A careful study of the crime scene is very crucial, and it determines the rest of the investigation. The injuries found on the body indicate the weapon used to cause the injuries, the hair found on the floor identifies the person who was at the crime scene, etc. In the same vein, building a logical relation from a conclusion enables one to know what needs to be proven, and thus what needs to be done to deliver the proof.
Besides creating a base for an effective inference, starting from a conclusion also creates a base for an effective distinction between evidence and data. Since the truth of a conclusion is to be proven by some premise or premises, and since the conclusion is an inferential product of the premise(s), the key to identifying whether or not a premise is relevant to the proof is to see whether or not it shares basically the same set of truth conditions as the conclusion. Thus the truth conditions shared by the premise(s) and conclusion form the basis of the relevancy. And the trick to building a convincing argument is the establishment of a same set of truth conditions across the premise and conclusion in the argument. The details about how to find the premise that shares the same truth conditions are too long to be presented in this paper. A step-by-step guidance on how to do it is provided for the students who take the course.