Logic is the science of techniques, laws, and forms of thinking. Formal logic was developed by the ancient Greeks long before our era. It was the Greeks who were the first to build a democratic society where decisions and laws were adopted at public meetings. At a primitive level, they created the science of litigation. A favorite pastime of aristocratic youth were discussions with philosophers. Hence the universal love for the development of theoretical sciences. The Greeks simply needed a teaching on how to cost scientific evidence.
The first course of the basics of logic was developed by Aristotle. He drew attention to the fact that any reasoning is based on general laws, violation of which leads to erroneous conclusions. Aristotle's formal logic was based on such laws:
- If the judgments are affirmative, the conclusion drawn from them cannot be negative.
- If one of the statements is negative, then the general conclusion will always be negative.
It follows that formal logic is knowledge of the principles and laws of effective, proper construction of reasoning, taking into account the form of their construction (ways of connecting the individual parts of the general reasoning).
All phenomena and objects are interconnected. Relations can be objective or subjective, general or private, necessary or random. The most significant of these relationships are called laws. All of them reflect the same reality, therefore, they can in no way contradict each other. All the laws of human thinking are connected with the laws of the development of nature.
The laws of thinking are a stable internal connection between thoughts. If a person cannot connect his thoughts, then he will not come to the correct conclusion and will not be able to convey it to others.
The basic laws of formal logic are the laws of consistency, identity, exclusion of the third, and the law of sufficient reason. The development of the first three belongs to Aristotle and Plato, the latter to Leibniz. Violations of these laws (especially the first three) lead to contradictions, making it impossible to distinguish truth from lies. The latter law is less normative and is applied more restrictively.
Non-basic laws of logic are the rules for operating with judgments and concepts, obtaining a true conclusion in syllogism, increasing the likelihood of conclusions being inductive and traduction inferences.
The law of consistency means that thinking should not be contradictory, but should reflect the qualitative certainty of things.
The law of the excluded third prescribes not to search between the two conflicting, but true statements, something third, but to recognize the truth of only one of them. One of the components of the contradiction is certainly true.
Formal logic interprets the law of identity as a requirement of thinking accuracy, that is, by any term you need to accurately understand its definition and meaning. The essence of concepts and judgments cannot be distorted at will.
The law of sufficient reason is that any true thought must be justified by other true thoughts, and false thoughts cannot be justified. In the development of judgments, a causal relationship should be reflected. Only in this case can its reliability be proved.
The logical form of thought and methods for determining the forms of any thoughts are expressed using logical terms, which include the unions “and”, “or”, “if ... then ...”, the negation of “it is not true that” (“not”) , the words “some”, “all” (“none”), the link “essence” (in the meaning of “is”), etc. It is possible to reveal the logical form of judgment, being distracted from the meaning of illogical terms that are included in the verbal expression of this judgment. In other words, formal logic expresses the structure of thought. The logical form is always informative and informative.
Depending on their forms, thoughts are divided into classes: concepts, conclusions and judgments. A concept is a thought generalizing objects based on their basic attributes. A judgment is a thought affirming the presence (absence) of a state of affairs. Inference is a thought reflecting the acquisition of knowledge, expressed in judgments, from other knowledge.