Hypothetical logical reasoning question, what are the three logical forms of hypothetical reasoning?

There are two kinds of hypothetical propositions: one is a sufficiently conditional hypothesis, and the other is a necessary conditional hypothesis.

The proposition in your question is a sufficiently conditional hypothetical proposition. Then, there are two effective ways to justify the sufficiency conditional hypothesis: one is to affirm the antecedent:

If a, then b, now known a, so b; Rather, it negates the posterior: if a, then b, is now known to be non-b, so non-a can be deduced.

For a sufficiently conditional hypothetical proposition, it is false only if its antecedent is true and its subsequent is false; Otherwise, it's true. For example, if it rains and the meeting is not postponed, it is false, and all other cases are true.

For the sake of understanding, if it doesn't rain, why is it true that the meeting is postponed? It is not difficult to imagine that rain is a sufficient condition for the postponement of the meeting, but it is not necessary, so even if it does not rain, the meeting will be postponed for other reasons, such as the attendees not being able to show up on time.

Hope it works for you.

A proposition and its inverse proposition are the same as true or false, while its inverse and negative propositions are true or false.

Original proposition: If it rains, then the meeting is postponed.

No proposition: "If it doesn't rain, then the meeting won't be postponed" may be a false proposition.

The negation of a false proposition is a true proposition.

But "if it doesn't rain, then the meeting won't be postponed" may also be true.

Therefore, "if it doesn't rain, the meeting will be postponed" is just a possible proposition.

1. Hypothetical reasoning of sufficient conditions, the antecedent is a sufficient condition of the subsequent, that is: if the situation determined by the antecedent occurs, then the situation ascertained by the subcontractor must also occur, and if the situation determined by the antecedent does not occur, then it is uncertain whether the situation ascertained by the later precedent occurs

If you are complacent, then you will regress.

He was proud and complacent.

So he regressed.

In this example, "complacency" (the former article) is a sufficient condition for "regression" (the latter article).

2. The hypothetical reasoning of the necessary condition, the antecedent is the necessary condition of the posterior, that is: if the situation determined by the antecedent does not occur, then the situation ascertained by the subsequent part will not arise, and if the situation determined by the antecedent occurs, then it is uncertain whether the situation ascertained by the subsequent part occurs

It can only be realized if the ideal is put into action.

He did not put his ideals into action.

So he did not live up to his ideals.

In this case, "putting into action" (the previous article) is a necessary condition for "realizing the ideal" (the latter article).

3. Hypothetical reasoning of sufficient necessary conditions, the antecedent is a sufficient necessary condition of the latter: if the situation determined by the antecedent has occurred, then the situation ascertained by the subsequent has necessarily occurred, and if the situation determined by the antecedent has not occurred, then the situation determined by the subsequent has not occurred

A number is divisible by 2 if and only if it is an even number.

a.This number is divisible by 2. b.This number is not divisible by 2.

So it's an even number. So it's not an even number.

In this example, "divisible by 2" (antecedent) is a sufficient and necessary condition for "even" (posterior).

A hypothetical judgment (proposition) is a compound judgment that asserts the conditional relationship between things and situations. It is a proposition that asserts that the existence of one thing condition is a condition for the existence of another thing condition. There are many kinds of connections between objective things and phenomena, some of which are conditional connections.

A hypothetical judgment is a judgment that reflects the conditional relationship between things and phenomena. It is usually expressed by hypothetical complex sentences and conditional complex sentences.

For example: (1) If the hands rub together, then heat will be generated.

2) If there are no rain clouds, it cannot rain.

Both judgments are hypothetical judgments. In example (1) and example (2), "two-handed friction" and "rain clouds" both indicate conditions, indicating the support judgment of conditions, and logically call it antecedent; "It will generate heat" and "it can rain" both indicate that the branch judgment is established by relying on the condition, and the branch judgment that is established by the dependent condition is logically called the "posterior"; "If ......Then ......"If you don't ......It's not ......" is a nexus. The hypothetical judgment is composed of three parts: the antecedent, the posterior, and the connecting item.

A hypothetical proposition is reasoning. 1. There are two rules for sufficiently conditional hypothetical reasoning:

To affirm the former, it is necessary to affirm the poster; If the former is denied, the latter cannot be denied.

To deny the latter is to deny the predecessor; Affirm the latter, not the predecessor.

2. The rules of hypothetical reasoning of necessary conditions.

There are two rules that must be followed by prerequisite reasoning:

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

Affirmation of the antecedent cannot affirm the latter, negation of the latter, and negation of the antecedent cannot be carried out.

Definition. The so-called hypothetical proposition is a proposition that states that the situation of one thing is a condition of the situation of another thing, and the hypothetical proposition is also called a conditional proposition. The compound proposition of "if a then b".

Also known as conditional propositions. The sub-proposition that represents the condition is called the antecedent, and the sub-proposition that represents the result is called the posterior. A hypothetical proposition states that the condition of one state of things is the condition of another.

In formal logic, the propositional conjunction "if," is understood to mean that "the antecedent is true and the latter is false" is false, i.e., "if a then b" is false, if and only if a is true and b is false; And when A is false, the whole compound proposition is always true. In modern logic, such a relationship between the truth and falsehood of propositions is called substantive entailment. In everyday language, there are other meanings about "if, then" such as causal connection, inferential relationship, and so on.

Necessary Hypothetical Reasoning is reasoning based on the logical nature of a Necessary Conditional Hypothetical proposition.

There are two rules for sine factual reasoning:

Rule 1: If you deny the antecedent, you must negate the posterior; Affirm the antecedent, not the rear.

Rule 2: If you affirm the latter, you must affirm the antecedent; If the latter is denied, the former cannot be denied.

According to the rules, there are two correct forms of necessary hypothetical reasoning:

1) Negate the antecedent.

Only p, only q

Non-p So, non-q

2) Affirmation post-piece formula.

Only p, only q

q So, p

For example:1Only those who have reached the age of eighteen have the right to vote; Xiao Zhou is less than eighteen years old, so Xiao Zhou does not have the right to vote.

2.Only by selecting excellent varieties can wheat be harvested; The wheat harvest is abundant, so the wheat field is of excellent variety.

Examples 1 and 2 are both necessary conditional hypothetical reasoning, with the former negating the antecedent; The latter is affirmatively posterior. Both of these inferences are in accordance with the rules of reasoning, so they are both correct.

According to the rules, both the affirmative antecedent and the negative posterior of the necessary condition hypothetical reasoning are invalid. For example:

3.Only if there is a motive to commit a crime, will he be a criminal; Someone has a motive to commit the crime, so someone must be the perpetrator.

4.Only with excellent academic performance can you be a good student; Xiao Wu is not a good student, so Xiao Wu's academic performance is not good.

Both Examples 3 and 4 are incorrect necessary presumptive reasoning because Example 3 violates the rule of "affirming the antecedent, not the posterior"; Example 4 violates the rule that "the latter cannot be negated".

Sufficiently conditional hypothetical reasoning is reasoning based on the logical nature of sufficiently conditional hypothetical propositions.

There are two rules for sufficiently conditional hypothetical reasoning:

Rule 1: If you affirm the previous item, you must affirm the later item; If the former is denied, the latter cannot be denied.

Rule 2: Affirm the latter, not the predecessor; To deny the latter is to deny the predecessor;

According to the rules, there are two correct forms of sufficiently conditional hypothetical reasoning:

1) Affirm the previous formula.

If p, then qp

So, q2) negates the posterior formula.

If p, then q is not q

So, non-p e.g

1.If anyone is complacent, then he will fall behind; Xiao Zhang is proud and complacent, so Xiao Zhang must fall behind.

2.If anyone has pneumonia.

He must have a fever.

Xiao Li didn't have a fever, so Xiao Li didn't suffer from pneumonia.

Examples 1 and 2 are both sufficiently conditional hypothetical reasoning, with the former being an affirmative antecedent; The latter is a negation of the posterior. Both of these inferences are in accordance with the rules of reasoning, so they are both correct.

According to the rules, both the negative antecedent and the affirmative posterior of sufficiently conditional hypothetical reasoning are invalid. For example:

3.If the landed object is not affected by external forces, then, it does not change the direction of landing; The object is affected by an external force, so it changes the direction of landing.

4.If Zhao is a smuggler.

Then, he should be punished by law; After investigation, Zhao was indeed punished by law, so Zhao was a smuggler.

Examples 3 and 4 are both incorrect sufficient conditional hypothetical reasoning, because Example 3 violates the rule of "negating the antecedent, not negating the latter"; Example 4 violates the rule of "affirming the latter, not the antecedent".

Sufficiently necessary hypothetical reasoning is reasoning based on the logical nature of sufficiently necessary hypothetical propositions.

There are two rules for sufficiently necessary hypothetical reasoning:

Rule 1: If you affirm the previous item, you must affirm the later item; To affirm the latter, it is necessary to affirm the predecessor.

Rule 2: To deny the antecedent, it is necessary to negate the posterior; To deny the latter is to deny the predecessor;

According to the rules, there are four correct forms of sufficiently necessary hypothetical reasoning:

1) Affirm the previous formula.

p if and only if q

p So, q

2) Affirmation post-piece formula.

p if and only if q

q So, p

3) Negation of the antecedent.

p if and only if q

Non-p So, non-q

4) Negate the posterior formula.

p if and only if q

Non-q So, non-p

For example:1A number is even if and only if it is divisible by 2; This number is even, so it is divisible by 2.

2.A number is even if and only if it is divisible by 2; This number is divisible by 2, so this number is even.

3.A number is even if and only if it is divisible by 2; This number is not even, therefore, this number is not divisible by 2.

4.A number is even if and only if it is divisible by 2; This number is not divisible by 2, so, this number is not even.

Examples 1 to 4 are the four correct inferences for the above sufficient and necessary hypothetical reasoning, respectively.

Summary. Dear, glad for your question. To some extent, all reasoning is not hypothetical reasoning.

The so-called hypothetical reasoning is reasoning based on the logical nature of the hypothetical proposition. There are three types of hypothetical reasoning: sufficient conditional hypothetical reasoning, necessary conditional hypothetical reasoning, and sufficient necessary conditional hypothetical reasoning. The negation of antecedents refers to the negation of the antecedents of the major premises in the minor premise, and the negation of the posterior of the conclusion in the form of the minor premise.

Reasoning, on the other hand, is based on the existing evidence and actual situation, and it is more based on an objective and practical condition.

Dear, round rough guess glad your question. To some extent, all reasoning is not hypothetical reasoning orange. The so-called hypothetical reasoning is reasoning based on the logical nature of the hypothetical proposition.

There are three types of hypothetical reasoning: sufficient conditional hypothetical reasoning, necessary conditional hypothetical reasoning, and sufficient necessary conditional hypothetical reasoning. The negation of antecedents refers to the negation of the antecedents of the major premises in the minor premise, and the negation of the posterior of the conclusion in the form of the minor premise. Reasoning, on the other hand, is based on the existing evidence and the actual situation, and it is more based on objective and practical conditions.

For example, hypothetical reasoning is also withdrawn through certain conditions, can we say that it is sufficient conditional hypothetical reasoning?

No, it's conjunctive reasoning.

Dear, the need for sufficient conditional hypothetical reasoning is supported by certain evidence, such as Bo Kongguo, if you can provide such corroborative cave silver core materials, then it can be said that it is sufficient conditional hypothetical reasoning.