Fallacy of: the Undistributed Middle vs Denying the Antecedent?

What type of fallacy is denying the antecedent?

Denying the antecedent, sometimes also called inverse error or fallacy of the inverse, is a formal fallacy of inferring the inverse from the original statement. It is committed by reasoning in the form: If P, then Q. Therefore, if not P, then not Q.

What is undistributed middle fallacy example?

Everyone who carries a backpack is a student.



It is undistributed because neither of its uses applies to all backpack carriers. Therefore, it can’t be used to connect students and my grandfather—both of them could be separate and unconnected divisions of the class of backpack carriers.

What is an example of denying the antecedent?

If you give a man a gun, he may kill someone. If he has no gun, then he will not kill anyone. If you work hard, you will get a good job. If you do not work hard you will not get a good job.

What is the fallacy of undistributed middle term?

The undistributed middle is a logical fallacy of deduction in which the middle term of a syllogism is not distributed in at least one of the premises. According to the rules of logic, a term is “distributed” when a sentence says something about everything the term designates.

What is the difference between denying the antecedent and affirming the consequent?

Affirming the antecedent (or Modus Ponens) involves claiming that the consequent must be true if the antecedent is true. Denying the consequent (or Modus Tollens) involves claiming that the antecedent must be false if the consequent is false. Both of these can be used in a valid argument.

Is modus tollens denying the antecedent?

While modus tollens denies the consequent of a conditional statement, denying the antecedent denies the antecedent of a conditional statement.

How does denying the antecedent disrupt argumentation?

Since it is not a valid form of argument, it cannot prove that the position is false. But it can provide inductive evidence that this position is probably false. In this role, it is neither defective nor deceptive. Denying the antecedent provides inductive support for rejecting a claim as improbable.

Is denying the consequent a fallacy?


Denying the antecedent is the name of another invalid conditional argument form you should think of this as the invalid version of modus. Tollens. On the left is modus tollens which is valid on the

What is an example of denying the consequent?

For example, given the proposition If the burglars entered by the front door, then they forced the lock, it is valid to deduce from the fact that the burglars did not force the lock that they did not enter by the front door. Also called modus tollens.

What is fallacy of affirming the consequent?

Affirming the consequent, sometimes called converse error, fallacy of the converse, or confusion of necessity and sufficiency, is a formal fallacy of taking a true conditional statement (e.g., “If the lamp were broken, then the room would be dark”), and invalidly inferring its converse (“The room is dark, so the lamp …

Is denying the antecedent valid?

Like modus ponens, modus tollens is a valid argument form because the truth of the premises guarantees the truth of the conclusion; however, like affirming the consequent, denying the antecedent is an invalid argument form because the truth of the premises does not guarantee the truth of the conclusion.

Why is the fallacy of affirming the consequent a fallacy?

The fallacy of affirming the consequent occurs when a person draws a conclusion that if the consequent is true, then the antecedent must also be true. The consequent is the ‘then’ part of a conditional statement, though at times you won’t see the word ‘then’ used.

What is an example of affirming the antecedent?

For example, given the proposition If the burglars entered by the front door, then they forced the lock, it is valid to deduce from the fact that the burglars entered by the front door that they must have forced the lock. Also called modus ponens.

What is the meaning of affirming the antecedent?

‘Affirming the antecedent’ or ‘Modus ponens’ is a logical inference which infers that “if P implies Q; and P is asserted to be true, so therefore Q must be true.”

Why is affirming the antecedent valid?

Affirming the antecedent is a valid argument form which proceeds by affirming the truth of the first part (the “if” part, commonly called the antecedent) of a conditional, and concluding that the second part (the “then” part, commonly called the consequent) is true.

Is denying the disjunct valid?

To deny a disjunct and affirm the other disjunct as a conclusion is a validating form of argument in propositional logic which is called “disjunctive syllogism”―see the Similar Validating Forms, above.

Is affirming the disjunct a fallacy?

It is a fallacy of equivocation between the operations OR and XOR. Affirming the disjunct should not be confused with the valid argument known as the disjunctive syllogism.

What is disjunction fallacy?

Disjunctive fallacy results from thinking that within a choice between two things, finding one thing true makes the other thing false (even though they might both be true).

What is affirming a disjunct example?

An example of affirming a disjunct would be: I am at home or I am in the city. I am at home. Therefore, I am not in the city.

What is an example of disjunctive syllogism?

Disjunctive Syllogism Examples



This cake is either red velvet or chocolate. Since it’s not chocolate cake, it must be red velvet. Either Statement: This cake is either red velvet or chocolate. False Premise: It’s not chocolate.

What is a disjunction critical thinking?

A disjunction is an “or” sentence. It claims that at least one of two sentences, called disjuncts, is true. For example, if I say that either I will go to the movies this weekend or I will stay home and grade critical thinking homework, then I have told the truth provided that I do one or both of those things.