What is the general form of hypothetical reasoning?

Hypothetical reasoning is based on a hypothetical judgment, and conclusion reasoning is deduced according to the relationship between the antecedents of hypothetical reasoning. According to the different preconditions of hypothetical reasoning, it can be divided into sufficient conditional hypothetical reasoning, necessary conditional hypothetical reasoning and sufficient and necessary conditional hypothetical reasoning. Hypothetical reasoning is based on the relationship between the antecedents of hypothetical judgment, and at least one of its premises is hypothetical judgment.

(1) Sufficient conditional hypothetical reasoning is hypothetical reasoning with sufficient conditional hypothetical judgment as one premise and blunt judgment as another premise and conclusion. It has two correct forms: positive beforehand and negative afterwards.

The formula for affirming the antecedent is: if P, then Q; P, so, Q. For example, if anyone is conceited, he is behind the times; Xiao Zhang is conceited, so Xiao Zhang is bound to fall behind.

The formula for denying the latter formula is: if P, then Q; Non-q; So, it's not P. For example, if someone has pneumonia, he must have a fever. Xiao Li has no fever, so Xiao Li has no pneumonia.

Sufficient conditional hypothetical reasoning has two rules:

(a) Affirming the former means affirming the latter, while denying the latter means denying the former;

(2) Negating the antecedent cannot deny the latter, and affirming the latter cannot affirm the antecedent.

If you break the rules, the reasoning is wrong. For example, if someone has pneumonia, he must have a fever, and Xiao Zhao has a fever, so Xiao Zhao has pneumonia. This conclusion is not reliable, because there are many causes of fever, and Xiao Zhao's fever is not necessarily caused by pneumonia. Rule (2) points out that the former cannot be sure of the latter, but here, it is wrong to go from the latter to the former.

(2) Hypothetical reasoning with necessary conditions takes hypothetical judgment with necessary conditions as one premise and blunt judgment as another premise and conclusion. It also has two correct forms: negative beforehand and positive afterwards.

The formula for denying the above clause is: only P, only Q, not P, so it's not Q. For example, only those who have reached the age of 18 have the right to vote, while Zhou Xiao is under 18, so Zhou Xiao has no right to vote.

Affirm that the formula of the latter formula is: only P, only Q, Q, so, P, for example, only a good variety can be selected for a bumper harvest of wheat, so this wheat field has chosen a good variety.

There are two rules in hypothetical reasoning of necessary conditions: (1) Denying the antecedent means denying the antecedent, and affirming the antecedent means affirming the antecedent; (2) Affirming the former cannot affirm the latter, and denying the latter cannot deny the former.

If you break the rules, your reasoning is wrong. For example, good academic performance can be a three-good student; Xiao Wu is not a good student,

It can be seen that Xiao Wu's academic performance is not excellent. This conclusion is also unreliable, because rule (2) points out that denying the latter cannot deny the former. Here,

It is just from denying the latter to denying the former, so it is wrong.

(3) Necessary and sufficient conditional hypothetical reasoning takes one premise of the necessary and sufficient conditional hypothetical judgment as hypothetical reasoning, and the other premise and conclusion of the blunt judgment hypothetical reasoning as hypothetical reasoning. It has four correct formulas.

Affirmative antecedent: if and only if p, then q; P, therefore, Q. affirms the latter formula: Q if and only if P; Q, so, p. Negative antecedent: Q if and only if P; It is not P, so it is not Q. Negative posterior formula: if and only if P, then Q; It's not q, so it's not p.

This reasoning also has two rules: (1) affirming the former means affirming the latter, and denying the latter means denying the former; (2) It is necessary to deny antecedents.

To deny the latter and affirm the latter is to affirm the former.

Two. Unless there is any difference in the logical relationship between them ... unless ...?

Unless the logical relationship between them ... unless ... is different:

(1) B Relationship: -B Subtract A unless A. I want to marry you unless you buy me a diamond ring. Not to marry you and buy a diamond ring.

(2) Unless A, it doesn't matter. B: -(-B) Push A, that is, B pushes A. Unless you buy me a diamond ring, I won't marry you. Marry you and buy a diamond ring.

(2) Extended reading of the necessary conditional reasoning formula:

Unless it's p, it's not q? For example, we can give an example of marriage, "I won't marry my daughter to you unless you give me 500 thousand."

That is to say, "My daughter marries you" can be deduced as "giving a bride price of 500,000 yuan". The most common problem of old students is that this keyword "no" is part of logical related words and does not represent negative symbols. In other words, "unless P, it is not Q" and "unless P, it is not Q at all".

Unless ... Examples of sentences are as follows:

(1) You will never be a loser unless you stop trying.

(2) Unless you get a negative answer in the first visit, you will have a chance to create a second meeting.

(3) Unless you want to be first-rate, you are second-rate.

Examples of not making sentences unless ... as follows:

(1) You don't know what happiness is unless you have love.

Unless you stop trying, you won't fail.

(3) Unless it is the stupidest mouse, it will not hide in the cat's ear; But unless you are the smartest cat, you won't search your ears.

Ⅲ Can anyone explain the concepts and forms of sufficient conditions, necessary conditions and necessary and sufficient conditions, and the reasoning formulas derived from them?

The sufficient conditions for b and a to be b are deduced from a.

Deduce a from b, and a is a necessary condition for B.

Both push each other at the same time, and A and B are necessary and sufficient conditions for each other.

As for the deduced reasoning formula, you should know the basics first, and then ask me. I am a master of formal logic, and you have learned the basics. Depending on your research spirit, you can become a detective and a scientist.

Ⅳ The logic of civil servants is too poor to understand. Seek expert advice, formulas and examples for complex propositions. . . And how to learn logical reasoning.

Hello, Chinese public education is at your service.

There are three kinds of complex propositions: joint propositions, alternative propositions and hypothetical propositions.

First, joint propositional reasoning

A joint proposition is a proposition that combines several propositions to show that these situations exist at the same time.

It can be expressed as: p and q(p and q are conjunctions, and "he" is a conjunction).

Conjoined proposition has two inference rules:

1. All limb propositions are true and joint propositions are true;

2. If the joint proposition is true, it can be inferred that any one of the limb propositions is true.

For example, "you are tall" and "you are handsome" can lead to the joint proposition of "you are tall and handsome"; "You are tall and handsome" can also introduce "You are tall and handsome".

Second, selective propositional reasoning.

Choosing a word proposition is to give several propositions, and you can choose one or more existing propositions. According to the different situations that can be selected, it can be divided into two types:

Compatible substitution proposition: multiple situations can exist at the same time.

It can be expressed as: p or q(p and q are optional limbs, and "or" is a conjunction).

Incompatible alternative proposition: only one situation is allowed.

It can be expressed as: either P or Q (both P and Q are optional limbs, and "either ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

The reasoning of compatible and incompatible selection rules is as follows:

In fact, the logic problem is not very difficult, but you should know that the logic problem has its inherent logic. You just need to learn the relevant reasoning rules. Some logic is reasonable in the topic, but you will find that it is unreasonable in common sense, but the logical topic does not conform to your cognition, but to the logic of the topic.

There is a course in the university called logic, you can learn it ~ ~

Good luck ~ ~

If in doubt, please consult the public education enterprises in China.

Ⅳ What are the meanings of "unless A, otherwise B" and "A, unless B" in hypothetical logic?

"unless a, it's b": unless a happens, it's all B.

"A, unless B": A appears in most cases, and A does not only appear when version B appears. correct

"Unless A, B" means affirming the former, and affirming the former means affirming the latter; Deny the former, not the latter.

"A, unless B" is negative, affirmative and uncertain; If you deny the latter, you must deny the former.

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Hypothetical reasoning is based on the logical nature of hypothetical propositions, also known as hypothetical logic, which can be divided into three types: sufficient conditional hypothetical reasoning, necessary conditional hypothetical reasoning and sufficient and necessary conditional hypothetical reasoning.

Sufficient conditional hypothesis reasoning is based on the logical nature of sufficient conditional hypothesis proposition.

Sufficient conditional hypothetical reasoning has two rules:

Rule 1: To affirm the former, we must affirm the latter; Deny the former, not the latter.

Rule 2: affirm the latter, but not the former; If you deny the latter, you must deny the former.