Although sad, it does seem true that today, Logic is a much loved and little used discipline. The reasons for this are no doubt complex and I will not take time here to search them all out. Nevertheless, there is one outstanding reason which I hope to begin to address by the method and matter of this course on Logic.

The basic problem is that we have lost all sense of learning a skill or discipline. Today students do not learn "disciplines"; they study "subjects." The fact of the matter is that modern popular education places more importance on knowing facts about things than in learning and practicing skills of thought and communication. The modern school system is a monument to the strength of this conclusion. In this course, I do hope to introduce to you the facts of logical theory, but I also hope that I will teach you to learn a skill. I want you to take Logic outside the classroom and be able to use it.

Logic is a tool. In fact, it might be more properly said that it is a toolbox. In this toolbox there are a number of different kinds of tools. Some who have studied Logic elsewhere will have some questions about the definition of Logic that I have chosen to use in this course. Often the definition of Logic includes the word "correct", as in "Logic, the art of correct reasoning," or "necessary," as in "Logic, the science of necessary inference." While these definitions are useful in their own right, they weight the study of Logic too heavily in the direction of only one kind of human reasoning--the deductive. In order for an art to be truly fruitful it must speak to the whole subject before it specializes, not after. Doctors don’t start out training in a specialty and then go on to Anatomy 101. Likewise, for the beginning logician to learn deductive reasoning apart from a basic understanding of the other kinds of legitimate inference that humans practice is to set him up for a very shallow, and at points mistaken, use of whatever he does learn about logic. Until the student understands where we get premises like "Whatever goes up must come down," "man is a featherless biped," and "nothing is sure but death and taxes," he will not be able to understand or evaluate reasoning well. To define Logic as the art of necessary inference is to rule out the inductive reasoning that leads us to many of the general statements we deduce from in deductive thought. How do I come to the premises in the following basic but much used course of reasoning? "Light switches turn on lights: this is a light switch: therefore, if I flip this light switch, it will turn on the light." This process happens so quickly after we do it a few thousand times that it ceases to seem like thinking. And, as many of us have realized with alarm when we flip a light switch and the garbage disposal comes on, there are exceptions. Despite the fact that this doesn’t seem like reasoning and its conclusion is not universally true, both deductive and inductive reasoning are involved in this process.

The logical tool box contains a number of different reasoning tools. Most prominent in the formal study of Logic is deductive reasoning, which is linear reasoning from general statements to a more particular conclusion. For example: All men are mortal (general statement); Socrates is a man; therefore, Socrates is mortal (particular conclusion). The other type of reasoning I have mentioned, inductive reasoning, is linear reasoning from particulars to a general conclusion. For example: you might choose to observe the color of various crows over the course of a week. Having noticed that this crow, and that crow are both black--in fact, every crow you have seen has been black (particular observations)--you feel justified in concluding that all crows are black (general conclusion).

Of the two, inductive reasoning is much less popular for the study of logic, partially because it produces conclusions which are not, strictly speaking, true or false; rather, they are strong or weak. Logic is valued by many for its universal and unchanging consistency. The Modus Ponens form of argument is always valid in a very similar way to that in which 2 + 2 always equals 4. This unchanging status of logical validity and mathematical relationship is justly admired. However, inductive reasoning is also a legitimate and necessary part of human reasoning, and there is a Biblical basis for it. Inductive reasoning will, therefore, be included in this course as a necessary counterpart to the generally more "foolproof" deductive argumentation. In addition to both of these, I will also spend some time exploring some kinds of parallel reasoning. It is my conviction as both a teacher and a student that it is high time for Christians to begin studying parallel reasoning, if for no other reason that our Lord and Savior was so fond of parables and of teaching by analogy.

So in this course I hope to teach the student how to recognize and evaluate different kinds of reasoning, from the precise necessary inferences of categorical calculus to the dynamic necessities and limitations of analogy. One of the most important lessons of Logic comes in learning that each of these areas of study both possesses great potential and suffers certain limitations. One of the ways I like to describe to students the role of Logic (especially deductive) in the world is to compare it to mathematics. While math concerns the study and representation in symbolic form of the causal relationship between physical objects, Logic has to do with the study and representation in symbolic form of the causal relationship between words and concepts. I use this comparison to point out that, while mathematics is a good way to work out the causal relationships between things, the things themselves are not the same as the mathematical language used to describe them. In a similar way human thought--concepts, words, and intuitions--are more than, not less than or the same, as the logical analysis we perform in an attempt to understand them. This course teaches the "theory" of reasoning, which will help the student find and understand more clearly the logical connections between concepts and words.

Theory is the first step to proficiency in almost any discipline. Ad Herenium, a treatise on rhetoric of unknown authorship, gives three steps to gaining proficiency at rhetoric: theory, imitation, and practice. These are actually the three steps to proficiency at anything, including the Christian life. For Christians (after conversion), progress in the faith follows this pattern. First we learn the doctrines and the distinctives of Christian belief. Then we imitate Christ and those others who imitate Him--Christian brothers and sisters. Finally, we are faced with the necessity of practicing our faith on our own as we endeavor to please God in Christ. This is theory, imitation, and practice. The universal nature of these three steps can be seen almost anywhere. Since I am trying to help the Logic student both to learn and to apply the principles of logic, these three steps will play an important role in this course. Although I will emphasize Theory, especially at first, eventually we will spend significant amounts of time studying and appreciating the good arguments in the Bible and in the classics of literature and theology. By the end of this course, the student will be asked to apply his newly gained logical skills in certain real-life situations.

Students, I hope you will undertake this study as a discipline. To know the anatomy of reasoning and the basic building blocks of the causal system is half the battle. After you have been forced to use them, by rote at first, and then creatively by the end of this course, my hope and expectation is that you will have a foundation on which it is only natural to build. First, however, you must acknowledge and enjoy God’s glory in all things; this is no less true in Logic than in the rest of life. Since this has served as my foundation, you will spend very little time exploring the metaphysical basis for knowledge or the certainty of knowledge. For the Christian it need not be complex. God has revealed and is revealing His glory to men; this is how we know what we know. The certainty of our knowledge is dependent on Him and, in my opinion, we must live like Augustine, believing in order that we might understand. With a starting point there are places to go, and in God and His Word we have a solid starting point. This does not mean that all of God’s Word is easy to understand; it merely means that it is true and that enough of it is clear enough that we can, by God’s grace, spend the rest of our lives seeking to understand the rest.

Some will argue for the divine origin of logic, claiming that it is part of God’s nature. While I understand and concur with many of the reasons for this claim, I do not think it is necessary to uphold the legitimacy of Logic or its importance in this way. The connection of Logic or mathematics with God’s nature seems to me to be driven more by the appreciation of the universal nature of the principles of each (as per above) than by the actual teaching of the Bible. It is clear that God "thinks," and that He does not lie; in fact, He is the Truth. But to go beyond that to say that reasoning in humans is not a created phenomenon is to make philosophical leaps. This is not to draw too sharp a distinction between God’s thoughts and ours; rather, it is to moderate and caution those who are too eager to step up to the defense of logic. Logic needs no defense; it is a human necessity, like breathing, and just as He sustains our breath God also sustains our thoughts. Place it there, in God’s hands. This is the only safe way to handle what has been, for many, a dangerous idol. Logic and reason are a gift from God, a gift by which we interact with the world and His Word. For this reason Christians ought to study Logic and reasoning; they ought to know it like they know how to eat or sleep. The art of finding the intelligible connections between words and concepts is well worth your time as a human and as a Christian, so enjoy it.

This course is based on the textbook, Practical and Symbolic Logic, written by Peter Roise.