Logic
Logic deals with the methods of valid thinking. It reveals how to draw proper conclusions from premises and is a prerequisite of all thought. In fact, it builds from fundamental laws of reality and truth, the principles that make rational thought possible (see First Principles). Logic is such an indispensable and inescapable tool for all thought that even those who eschew it still use logical forms to argue for their rejection of it (see Fideism).
The three fundamental laws of all rational thought are:
1. the law of noncontradiction (A is not non-A),
2. the law of identity (A is A), and
3. the law of excluded middle (either A or non-A).
Each serves an important function. Without the law of noncontradiction we could say that God is God, and God is the Devil. Unless the law of identity is binding, there can be no unity or identity. Without it there is no difference in stating, “I am I” or am a chair.” If the law of excluded middle does not hold, then opposites could both be true.
Example
These are given not just as nice rules of thumb to follow or ways that one should think. Aristotle identified these as necessary conditions for thought. People sometimes try to produce counter examples to these Laws by pointing out how statements can become true or false depending on the conditions; e.g. “It is raining” might be true now, but was false yesterday” or “it is half way between raining and not-raining.” But these attempts always involve changing the reference of the statement. Once we get the reference of the statement clear and explicit, it does not seem possible for a statement to make sense and vioate these laws. At this point, the 2 thousand year debate over the nature of reference begins, and the shape of philosophy is drawn.
Former President Clinton tried to weasle the Laws of Thought when he denied that he had lied to Congress about whether “there is a relationship with my intern” by saying later “it all depends on what is is.” Like in the raining example above, he thought that he could make the truth of his stament change because the relationship had ended. Almost everyone could immediately see that he was twisting words beyond sense and digging himself into an even deeper deception. We can see this because logic involves conditions that are common to us all. Even Presidents cannot veto the Laws of Thought.
Sources
N. L. Geisler
Oregon State University
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