He put forward a hypothesis through rigorous reasoning and bold imagination, trying to explain the phenomenon of personality separation and free combination of different characters.
Then he cleverly designed a cross-test experiment to test the hypothesis. It is impossible to directly verify the hypothesis itself, but to verify the inference derived from the hypothesis, that is, if the hypothesis that genetic factors determine biological characteristics is established, then the results of the test experiment can be deduced and predicted theoretically according to the hypothesis; Then, the experimental data are compared with the theoretical derivation. If they are consistent, the assumption is correct; If they don't agree, the assumption is wrong.
Of course, the actual test process of hypothesis is very complicated, and it is impossible to explain the problem by one or two experiments alone. In fact, many experiments conducted by Mendel have obtained similar results. Later, several scientists made many observations similar to Mendel's experiment. After a large number of experiments verified the authenticity of Mendel hypothesis, Mendel hypothesis finally developed into a classic theory of genetics.
As we know, deductive reasoning is an important form of reasoning in scientific argumentation. Why can the consistency between experimental values and theoretical deduction prove the correctness of the hypothesis? Facts have proved that the phenotype and proportion of the offspring of test cross truly reflect the types and proportion of gametes produced by the offspring.
According to the gamete type of offspring, its genetic composition must be inferred, and revealing this mystery plays an important role in the process of deductive reasoning. Without revealing this mystery, it is difficult for students to understand the scientific and rigorous nature of "hypothesis-deduction method", and the conclusion of deductive reasoning still stays in the state of knowing it.
1900, three scientists rediscovered Mendel's work, and the genetics community began to realize the significance of Mendel's genetic theory. If Mendel's supposed genetic factor, the gene, does exist, then where is it? 1903, American geneticist Sutton found that the segregation of alleles, a pair of genetic factors assumed by Mendel, was very similar to the segregation of homologous chromosomes in meiosis.
According to the obvious parallel relationship between genes and chromosome behavior, Sutton put forward the hypothesis that genes are carried from parents to offspring by chromosomes, that is, genes are located on chromosomes. Morgan, an American geneticist, made it clear that he did not believe Mendel's genetic theory and doubted Sutton's hypothesis. Later, he did many fruit fly hybridization experiments, combining a specific gene with a specific chromosome. X chromosome, thus confirming Sutton's hypothesis.
It can be seen that the process of exploring the relationship between genes and chromosomes is also a hypothetical-deductive process.
Extended data
The role of deductive reasoning in scientific research includes three aspects:
(1) Use general principles or theories to guide scientific research. Without theoretical guidance, investigation and research will be blind and unsystematic.
② Deduce concrete and unknown phenomena from abstract theories. Deductive reasoning can link theory with empirical phenomena and predict some unknown phenomena.
(3) It is helpful to demonstrate or refute a theory.
In order to improve the reliability of the conclusion, we must pay attention to the following points:
1. The more known facts can be explained from the assumptions in the premise, the more reliable the conclusion (assumptions) will be. As far as the above example is concerned, if the patient has chest pain, rusty sputum and other phenomena besides fever, cough and dyspnea, then the hypothesis (conclusion) that the patient has pneumonia will be supported by more evidence and be more reliable.
2. The more predictions about unknown facts are derived from the hypothesis, and these predictions are later confirmed, the greater the reliability of the conclusion hypothesis, and the higher its probability.
For example, the "continental drift" hypothesis can further predict that the distance between the two sides of the Atlantic Ocean is gradually increasing, and the distance between Greenland and Greenwich is increasing due to its continuous westward movement. Later, the confirmation of these predictions improved the reliability of the hypothesis of "continental drift" to varying degrees.
3. The more rigorous and severe the empirical facts used to confirm the assumptions in the premise, the greater the reliability of the conclusions (assumptions).
4. If the explanation of the existing facts or the prediction of the unknown facts derived from the premise are inconsistent or contrary to the results of the observation experiment, the reliability of the conclusion (hypothesis) will be reduced and may even be overturned.
Hypothetical deductive reasoning plays an important role in understanding. Copernicus' Heliocentrism, Newton's mechanical theory, Darwin's theory of evolution, Mendeleev's periodic table of chemical elements, Einstein's theory of relativity, etc. Are based on hypothetical deductive reasoning.
Baidu Encyclopedia-Hypothesis Deduction
Baidu Encyclopedia-Hypothesis Deduction