I mentioned in the last post that I had co-written a logic text. The following is a draft of something that will be going into the next revision. Here tis:
In order to reason well, we have to assume certain things that never show up as particular items in our argument. They are simply (and quietly) assumed. For example, if you were putting together an argument about light bulbs or tricycles, it is very important that they not turn into something else (like a toaster oven or catcher’s mitt) halfway through the argument. If they did, the argument would just have to lie down and sob quietly. It could never get anything done.
Traditionally, these assumptions have been called the “laws of thought.” There is nothing wrong with the specific content of these assumptions, but for Christians, there is a significant problem with another deeper assumption lying beneath them. That assumption is that you can have laws without a lawgiver, and ultimately, that you can have reason apart from the triune God of Scripture. All you need to do, it is thought, is postulate some laws of thought, and off we go.
Because this is the case, we are going to begin by showing how these correct assumptions are actually grounded in the nature of the triune God, and how He revealed Himself in Jesus Christ. After we have done that, we will then be able to discuss the traditional terminology. The reason for doing this is that many modernists have been guilty of thinking that impersonal “laws” have authority in themselves, which of course they do not.
In order to deal with this, we will start with the basic Christian confession, which is that Jesus is Lord. When God reveals Himself in Christ, the decision that everyone has to make is whether to believe it or not. These are the only two options-faith or unbelief. This means that the statement Jesus is Lord must either be true or false. A faithful person confesses that it is true. An unfaithful person denies it as false. But God does not leave open the option of saying something like, “I believe that the higher reality of the lordship of Christ cannot be contained in our paltry categories of true and false, and so I cannot say whether I believe in Him or not.” Such a response is simple dishonesty masquerading as humility.
The fact that any statement is either true or false is one of the three basic laws of thought, upon which much of logic is based. This law of thought is called The Law of Excluded Middle, because it excludes the possibility of a truth value falling somewhere in the middle between true and false. Statements are either one or the other. If a statement is not true, then it is false, and vice versa.
As Christians we confess that God is triune. If asked, we would say, “Yes, that is true. God is triune.” Now if it is true that God is triune, then it must be true that God is triune. For ordinary people, in ordinary conversation, such rules are not thought to be necessary. But when people are fleeing from God, they will often take refuge in any folly. This assumption keeps people from changing the meaning of a term in the middle of an argument. If you are seeking to show from Scripture that God is triune, it is important that the word triune not take on the meaning of “six persons” halfway through the argument. Honesty requires the meaning of the word to stay put. In its traditional formulation, this is called The Law of Identity. This law simply states that if a statement is true then it is true. This law may be employed to answer the unbeliever who says, “Christianity may be true for you, but not for me.” No. If the Christian faith is true, then it is true.
The third law says that a statement cannot be both true and false. This is called The Law of Noncontradiction. Without this law, we could not argue for the exclusive truth of any statement which we hold. We could try to assert, for example, that “Jesus is God.” But our opponents could respond, “Oh, I agree that what you say is true. But it is also false.” We see that if we deny these laws, we lose even the possibility of rational discourse.
Think for a moment what would happen to our faith if we were to allow someone to deny these fundamental assumptions. If we confess “God in three persons, blessed Trinity,” someone who denied the law of the excluded middle could say that this wonderful confession is not true, and it is not false. It is just wonderful, and perhaps even a little inspiring. The one who denied the law of identity could say that “yes, it is true that God is a Father for you, but my truth is that She is a Mother.” And one who denied the law of noncontradiction could say that God is our Father, and, also, in the same way and in the same respect, He is not our Father. In other words, denial of these bedrock assumptions would make a hash out of the simplest Christian confession like the Apostles’ Creed.
Having said all this, there is an important warning. The Bible does assume that the Father is the Father, and not the Son. The Spirit is the Holy Spirit and not the Father. The Father is not “not the Father.” At the same time, the Bible also teaches that the Father perfectly indwells the Son, and the Son indwells the Father. Statements about the Father are not detachable from statements about the Son. Jesus said that if you had seen Him you had seen the Father.
Through a wooden application of these “laws” some logicians have gotten to the point where they cannot understand or appreciate poetry, metaphor, sacraments, or marriage. The world is full of “indwelling” and mutual partaking because this is also what our God is like. In our study of logic and reason, we must always leave room for mystery. We know that the Father is Father, and no one else. We know that the Father is not the Son. But we should also know that the Father revealed Himself perfectly in the Son.
Summary: Faithful reasoning assumes these three laws of thought. The Law of Identity says that if a statement is true, then it is true. The Law of Excluded Middle says that a statement is either true or false. The Law of Noncontradiction says that a statement cannot be both true and false.