Franklin, an American inventor, once drew an analogy between lightning in the sky and electric current on the ground: they all emit light of the same color, they all have noise when they erupt, they all have irregular radiation, they all move quickly, they all can shoot animals, and they all can make flammable materials burn; At the same time, we know that the current on the ground can be conducted through wires. It is inferred that lightning in the sky can also be conducted through wires. Later, this conclusion was confirmed by Franklin's famous kite experiment.
The logical form of analogical reasoning is as follows:
The composition of analogical reasoning has an objective basis. Objective things have many attributes, and these attributes are often interrelated. There may be internal relations between the A, B, C and D attributes of A thing. If object B and object A have the same properties of A, B and C, then it may also have the property of D.. However, things are not only similar, but also different. Although many properties of A and B are the same or similar, they are different things after all, and there will always be some differences. It is possible that the D attribute is only owned by A, not by B, as shown in the following example.
In the past, some scientists have compared Mars with the Earth. They think that the earth is a planet in the solar system, a sphere, revolving around the sun, with an atmosphere, moderate temperature, moisture and higher animals. Mars is also a planet in the solar system, a sphere. It revolves around the sun, has an atmosphere, and has moderate temperature and humidity. Therefore, there may be higher animals on Mars.
But later scientific research overturned this conclusion, indicating that the conclusion of analogical reasoning is probable.
Analogical reasoning is different from deductive reasoning. There are three differences:
First, thinking in different directions.
The thinking direction of most deductive reasoning is from general to individual, while that of analogical reasoning is from individual to individual.
Second, the scope of the conclusion is different.
The range of deductive reasoning conclusion does not exceed the range of premise conclusion, and premise contains conclusion; The conclusion of analogical reasoning is beyond the premise, and the premise does not contain the conclusion.
Third, the relationship between premise and conclusion is different.
Deductive reasoning is inevitable and analogical reasoning is possible.
Analogical reasoning and incomplete inductive reasoning have similarities and differences.
The same thing is that the scope of their conclusion is beyond the scope of the premise, which does not contain the conclusion, and the relationship between the premise and the conclusion is probable.
The difference is that the thinking direction is different. The thinking direction of inductive reasoning is from individual to general, and that of analogical reasoning is from individual to individual.
In order to improve the reliability of analogical reasoning conclusions, we should pay attention to the following points:
First, two or two similar things should have as many known properties as possible.
The more properties two things have in common, the closer they are in general properties, so the derived properties are more likely to be shared by two things, as shown in the following example.
In the preparatory stage of space flight, people often use dogs and monkeys for experiments. This is because dogs and monkeys have the most common physiological functions and life characteristics with people. According to their reactions caused by overweight or weightlessness in space flight, it is inferred that people have the same characteristics.
Because people and dogs, monkeys and other higher animals have many common characteristics, the conclusion drawn by analogy reasoning is more reliable.
Second, the relationship between the same attribute of two or two similar things and the derived attribute should be as close as possible.
The closer the relationship between the same attribute and the attribute deduced by analogy, the higher the reliability of the conclusion, as shown in the following example.
Li Siguang, a famous scientist, once inspected the geological structure in Central Asia, and found that this is a generated petroleum structure, which is bound to be related to oil reserves. Later, he made a long-term and in-depth investigation and study on the geological structure of Songliao Plain in northeast China, and found that the geological structure of Songliao Plain is very similar to that of Central Asia. Since there is a lot of oil in Central Asia, there will be a lot of oil in Songliao Plain of China.
Because the same attribute "geological structure" is closely related to the derived attribute "oil", this conclusion is highly reliable. Later, according to Li Siguang's theory, China exploited a lot of high-quality oil in Daqing.
Third, we should pay attention to whether there is an attribute in the analogy that is exclusive to the derived attribute.
If the analogy and the inferred attribute are mutually exclusive, then the inferred conclusion cannot be established, as shown in the following example.
In the history of science, people once compared the moon with the earth. They have many similar properties, which leads to the conclusion that the moon also has life. But later, people found that the moon has a great temperature difference between day and night, and there is no air and water, which is not suitable for living things at all, thus overthrowing the assertion that the moon has life. Later, a field trip to the moon by an artificial earth satellite confirmed this fact.
The conclusion that there is life on the moon is overturned because the attributes of "large temperature difference between day and night" and "no air and water" on the moon are mutually exclusive with the attributes of "life".
When using analogical reasoning, we should pay attention to avoid making the mistake of "mechanical analogy". The so-called "mechanical analogy" refers to the analogy based on the superficial similarity or accidental similarity of two things, so as to draw absurd conclusions, as shown in the following example.
Some theologians compare the world to a clock to prove the existence of God. They think that clocks and watches are structured and regular, and so is the world. Since clocks and watches are made by people, there must be a creator in the world, and this creator is God.
This is to compare two fundamentally different objects mechanically according to their surface similarity. This analogy is obviously wrong and illogical.
Analogical reasoning plays a very important role in scientific research, acquiring new knowledge and reasoning, which is embodied as follows:
First of all, analogical reasoning contributes to scientific discovery.
Many important discoveries in science are based on analogical reasoning, as shown in the following example.
Huygens, a Dutch scientist, compared the two physical phenomena of light and sound and found that they have many common properties: straight-line propagation, direct propagation in the same medium, refraction when passing through different media, reflection or diffraction when encountering obstacles, and so on. At that time, it was known that sound was a wave, so it was inferred that light was also a wave, which was later confirmed by scientific experiments.
Second, analogical reasoning is helpful to scientific experiments.
The simulation experiment in modern engineering technology has the ability of analogical reasoning. Replace the prototype with a model, and indirectly study the laws of the prototype through the model, as shown in the following example.
During the research and design of the large cable structure of Beijing Workers' Gymnasium (with a building diameter of 94m), two models with a diameter of 5m and18m were made for mechanical experiments. A large number of scientific data were obtained through experiments, which provided a reliable basis for the design of the museum.
Third, analogical reasoning contributes to scientific and technological inventions.
Many important scientific and technological inventions benefit from analogical reasoning. Bionics, which appeared in the 1960s, is essentially the application of analogical reasoning. Bionics is a science that imitates the special skills of biology and uses the structural and functional principles of biological systems to manufacture technical systems, as shown in the following examples.
According to the special function of frog's eye to accurately track air targets, scientists have developed an "electronic frog's eye" that can track satellites and monitor air targets. According to the bat's function of emitting and recovering ultrasonic waves, a radar which can measure and track flying targets in the air was invented.
Fourthly, analogical reasoning helps to acquire new knowledge.
Analogical reasoning can help people acquire new knowledge, as shown in the following example.
"Foreigners are closer to tourists, but far away from tourists." Beginners of ancient Chinese may not understand the meaning of "foreigner" in the text. Through comparison, it is found that "near" and "far" are antonyms, so it can be inferred that "easy" and "dangerous" should also be antonyms. Since "danger" means "precipitous", "barbarian" should mean "flat".
Fifth, analogical reasoning is helpful to reasoning.
Analogical reasoning plays a special role in reasoning, as shown in the following example.
Lanning, a former Canadian diplomat, was attacked by his political opponents when he was running for the state legislature: "He must be of China descent." Lanning retorted, "You grew up drinking milk. Do you have cow blood? " .
The political opponents of Lanning think that "whoever eats milk has his blood", so as to attack Lanning that "he must have China blood". Lanning refuted political opponents by imitating their thinking patterns. "You grew up drinking milk. Do you have cow blood? " The argument of political opponents is self-defeating.