Learning experience of general logic
-talk about the steps to solve reasoning exercises.
Logic is called the gymnastics of thinking, and this metaphor makes sense. Logic can really train people's rigorous thinking, thus improving people's logical thinking ability. But this ability can not be achieved by rote memorization, but by doing a lot of logical exercises. In this sense, learning general logic and learning mathematics have something in common, so the important way to learn logic is to do problems.
General logic exercises can be divided into six parts according to different contents: preface exercises, introduction exercises, judgment exercises, reasoning exercises, regularity exercises and argumentation exercises. Through practice, our students can achieve the purpose of using concepts clearly, judging appropriately, reasoning logically and demonstrating convincingly. Although the exercises in these parts are different. The purpose to be achieved is different, but the same thing in doing these questions is to accurately understand the concepts involved in the questions.
When doing similar type problems to distinguish constants and variables in logical structures, we must first master what constants are. What is a variable? Then determine which part of the problem is constant and which part is variable. We know that the constant term is an invariable term in the logical structure, which determines its nature. Variable is a variable item in logical structure, which can be replaced by concrete concepts or judgments. According to the definitions of constants and variables, the words "all" and "all" in exercises are the items that remain unchanged in the logical structure, which determines that this logical structure is the full name of positive judgment, so the words "all" and "all" are usually constant items. While "S" and "P" can be replaced by concrete concepts, such as "Marxist", "materialist" or "China" and "Asian", so they are variables.
Similarly, when analyzing the structure of blunt syllogism, we should also grasp the corresponding concepts: the major item is the predicate in the conclusion, the minor item is the main item in the conclusion, the premise with major item is the major premise, the premise with minor item is the minor premise, and some items in the major and minor premise are the middle items. (Of course, before that, you must know what is the subject, what is the predicate, premise and conclusion) and then analyze the structure of syllogism in the question.
Because the key part of general logic is reasoning, we will take a common problem in reasoning exercises as an example to talk about my understanding of the problem-solving steps of this kind of problem.
Example: point out what kind of reasoning is below, and explain whether it is correct and why.
(1) some poisoning is food poisoning, therefore, not some poisoning is not food poisoning.
(2) The length of life may be caused by genetic factors or acquired conditions; Xu's longevity has genetic factors, so his longevity is related to acquired conditions.
Step 1: After analyzing the structure, you can determine the type of reasoning, so you should analyze the structure before doing this kind of exercise.
1. Determine the premise and conclusion according to the related words (because, so). "Because" is followed by premise, "So" is followed by conclusion, and "Because" is preceded by conclusion.
2. Determine the judgment types of premises and conclusions according to constant terms. Example 1 The constant items in the premise are "Yes" and "Yes". The invariants in the conclusion are "no", "yes" and "no", which can confirm that this reasoning is blunt. The constant term in the premise of Example 2 is "maybe", so this is selective reasoning.
3. Write out the logical structure and point out its reasoning type. (1) Question: SIP ~-SOP. This is the direct reasoning of the straightforward judgment of the relationship. ② Question: pvq p ~-q This is the positive and negative form of compatible substitution reasoning.
Step 2: Point out whether the reasoning form is correct according to the corresponding reasoning rules.
The 1.( 1) problem is the inference of the antagonistic relationship at a lower level. According to the rules. This kind of opposition can't be the same as falsehood and truth, so it can be inferred from falsehood but not from truth; ② The problem is consistent alternative reasoning. According to the rule of compatible substitution reasoning, some substitution branches cannot deny that other substitution branches are certain, so positive-negative expressions cannot be used.
2. Point out the reason and answer right or wrong. The reasoning form of the problem is wrong, because the reasoning based on the antagonistic relationship of subordinates cannot be deduced from the truth. (2) The form of topic reasoning is wrong, because it violates the rule of compatible alternative reasoning: affirming some alternative branches cannot deny others. Make a logical mistake, compatibility or incompatibility.
These are some of my skills and experiences in learning logic. In a word, I think learning logic needs more practice. Practice makes perfect. Practice more and you will naturally master the problem-solving skills.