In our doctrine class we discuss classical arguments for and against the existence of God. One such argument is the Problem of Evil and goes something like this: “If God exists, then he is both perfectly good and infinitely powerful. If he is perfectly good, then he is willing to prevent evil. If he is infinitely powerful, then he is able to prevent evil. But if evil exists, then God is neither unwilling or unable to prevent it. Evil does exist. Therefore God does not exist.” We use a shorter truth table to show that this argument is indeed valid (or perhaps we write a proof for it). The students who have taken logic know that if an argument is valid, but the conclusion is false (as this obviously is), then at least one of the premises must be false. This leads to a fruitful discussion about which premise is false, and why. Is God infinitely powerful but not able to prevent evil because he cannot interfere with the free will of men? This is the choice of many modern evangelicals. Does God’s perfect goodness require that He is always willing to prevent evil? Reformed scholars would say no, and give counterexamples such as the crucifixion.

How do you take formal logic and apply it to real life during the dialectic stage? In other words, how do you move from the theory into practical application of what has been learned?

First, the obvious. We must teach logic-it’s definitions, theories and techniques-so that the students fully grasp these concepts. By its very nature logic is immediately applicable; every area of study in which conclusions are drawn from premises employ the techniques of logic. So students who fully understand these techniques will make their own application, just as students who understand mathematics, grammar, or the sciences naturally find applications of those subjects in their daily lives.

Second, we must teach tools of logic. These include techniques such as determining assumed premises in enthymemes, applying immediate inferences, identifying formal and informal fallacies, defining terms, developing and answering dilemmas, and using truth tables. The teacher must, for the students’ sake, distinguish all these tools from those lessons which are merely the means to an end, such as mood and figure, Venn diagrams, formal proofs, and so on. These latter lessons are helpful in their place, but everyone should honestly recognize their limited applicability outside of the classroom.

Third, we must give students examples of logic being applied. The teacher should not immerse the student in too many highly-symbolic lessons without occasionally surfacing for a breath of application in ordinary language. To be sure, as a symbolic language, logic, like mathematics, has a certain elegance or even beauty. But God has given us logic in order to apply it to the world around us, and we must lead students in showing how this is done. Point out to your students examples of informal fallacies in the newspaper, analyze enthymemes in the Bible to uncover the assumptions, show how Jesus uses and gets out of dilemmas, analyze Aquinas’s arguments with shorter truth tables.

Fourth, we must review and apply the tools of logic throughout the secondary curriculum. The students should see some of these being applied in different way in all their other classes. Certainly, courses like Geometry and Rhetoric will overtly re-teach many of the techniques learned in the logic class, but every subject will use some of the tools. Do not all teachers define terms for their students? Do not all draw premises form conclusions? All secondary teachers should learn enough logic to use the tools appropriate to their particular subjects.