Basic logical laws can be likened to the principles and rules in force in nature. However, they have their own specifics, even if they act not in the world around us, but in the plane of human thinking. But, on the other hand, the principles adopted in logic differ from legal norms in that they cannot be repealed. They are objective and act against our will. Of course, one may not reason in accordance with these principles, but then hardly anyone will consider these conclusions to be reasonable.
Logical law is a pillar of science, both natural and humanitarian. If in everyday life one can still indulge in a stream of feelings incompatible with the rules of constructing and developing thought, logical gaps can be allowed, then in serious works or discussions such an approach is unacceptable. For the foundation of any evidence base is the principles of true judgment.
What are these rules? Three of them were discovered back in ancient times by Aristotle: this is the principle of consistency, the rule of identity and the law of the excluded third. Centuries later, Leibniz discovered another principle - of sufficient reason. All three laws of formal logic described by Aristotle are inextricably linked. If we assume for a second that one link of mind-building is absent, then, like a house of cards, the others fall apart.
The law of the excluded third can be summarized as follows: “Tertium non datur” or “No third.” If we express two opposite maxims concerning one and the same object (or a series of objects, or a phenomenon), then one judgment will correspond to the truth, and the other will not. Between these statements it is impossible to build another third one that would reconcile the two main ones or serve as a connecting logical bridge between them. The simplest example of the excluded third is: “This thing is white” and “This thing is not white.” But he acts only when both opposing maxims were expressed about the same thing, about a given time and about the same relation.
The law of the excluded third comes into effect even when there is a counter or counter-incompatibility between judgments A and B. The first is a statement of the opposite point of view. For example, the propositions “Earth revolves around the Sun” and “Sun revolves around the Earth” are counter-judgments. A counter-narrative contradiction arises when the phrase A affirms, and B denies anything: “Fire warms” and “Fire does not warm.” Also, this contradiction occurs between private and general judgments when one is positive and the other is negative: “Some students already have diplomas” and “No students have a diploma”.
To thinking, especially scientific, special requirements are put forward: consistency, consistency of certainty. The law of the excluded third is a measure of the truth of our logical reasoning. For example, if we affirm that “God is all-good”, then the sentence “God arranged the eternal torment of hell for sinners” is meaningless. If we affirm that God created a place of eternal torment for anyone, then it cannot be said that He is Good. Since contradictory attributes cannot belong to God as the object of our conclusions, one of the two maxims given above is true, while the second is false. There is no third here.