ll rational discussions (even those about the existence or non-existence of God) require the prior foundation of logical absolutes. You’d have a hard time making sense of any conversation if the Laws of Logic weren’t available to guide the discussion and provide rational boundaries. Here are three of the most important Laws of Logic you and I use every day:
The Law of Identity
Things “are” what they “are”. “A” is “A”. Each thing is the same with itself and different from another. By this it is meant that each thing (be it a universal or a particular) is composed of its own unique set of characteristic qualities or features.
The Law of Non-Contradiction
“A” cannot be both “A” and “Non-A” at the same time, in the same way and in the same sense. Contradictory statements cannot both be true in the same sense at the same time.
The Law of Excluded Middle
A statement is either true or false. For any proposition, either that proposition is true, or its negation is true. There is no middle position. For example, the claim that “A statement is either true or false” is either true or false.
The logical rules are necessary in order for to examine truth statements. We also need them to point out when someone is reasoning illogically. Although these principles help us to discover truth, they alone cannot tell us whether or not a particular proposition is true. To see what we mean, consider the following logical argument:
1. All men are mortal.
2. Spencer is a man.
3. Therefore Spencer is mortal.
The self-evident laws of logic tell us that the conclusion, Spencer is mortal, is a valid conclusion. In other words, the conclusion follows necessarily from the premises. If all men are mortal and if Spencer is a man, then Spencer is mortal. However, the laws of logic do not tell us whether those premises, and thus the conclusion, is true. Maybe all men are not mortal; maybe Spencer is not a man. Logic by itself can't tell us one way or the other.
This point is more easily seen by looking at a valid argument that isn't true. Consider the following:
1. All men are four-legged reptiles.
2. John is a man.
3. Therefore John is a four-legged reptile.
Logically, this argument is valid, but we all know it isn't true. The argument is valid because the conclusion follows from the premises. But the conclusion is false because the first premise is false. In other words, an argument can be logically sound but still be false because the premises of the argument do not correspond to reality. So logic only gets us so far. Logic can tell us that an argument is false, but it cannot tell us by itself which premises are true. How do we know that John is a man? How do we know that men are not four-legged reptiles? We need some more information to discover those truths. We'll be building arguments along this line to prove the existence of God. So, I want you to study how logic and argumentation works at the grassroot level.
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