1. induction and deduction: induction refers to the principle of summarizing general conclusions from individual facts; Deduction is to draw individual conclusions from general principles and concepts. Induction is a method from individual to general; Deduction is a method from the general to the individual.
Mendeleev summed up the periodic law of chemical elements by induction on the basis of people's understanding of a large number of individual elements. Later, he predicted the chemical properties of some elements that had not been discovered at that time from the periodic law of elements, using deductive method.
2. Analysis method and comprehensive method: analysis is to divide the whole objective object into various parts, aspects, characteristics and factors and understand them. It is a way of thinking that divides the whole into parts and decomposes complex things into simple elements to study separately.
Analysis is a necessary step and means to understand the essence of things. The task of analysis is not only to decompose the whole into its components, but also to grasp the essence through phenomena and the inevitability through contingency.
3. Comparative analysis: Comparative analysis is also called analogy or analogy. It is a dialectical logical method to distinguish things or problems to understand their differences, characteristics and essence. When the data is insufficient for inductive and deductive reasoning, comparative analysis is more valuable. Kant said: "whenever reason lacks reliable reasoning ideas, analogy can often guide us forward."
4. Observation method: Observation method refers to a method in which researchers use their own senses and auxiliary tools to directly observe the research object according to a certain research purpose, research outline or observation table, so as to obtain information. Scientific observation is purposeful, planned, systematic and repeatable.
5. Literature research method: Literature research method is a method to obtain information by investigating documents according to certain research purposes or topics, so as to fully and correctly understand and master the problems to be studied. Literature research methods are widely used in various disciplines.