I have trouble understanding this fallacy: “If A, then B. Therefore if not-B, then not-A.”


What is the If Then fallacy?

Description: It is a fallacy in formal logic where in a standard if/then premise, the antecedent (what comes after the “if”) is made not true, then it is concluded that the consequent (what comes after the “then”) is not true. Logical Form: If P, then Q.

What are 4 types of logical fallacies?

15 Common Logical Fallacies

  • 1) The Straw Man Fallacy. …
  • 2) The Bandwagon Fallacy. …
  • 3) The Appeal to Authority Fallacy. …
  • 4) The False Dilemma Fallacy. …
  • 5) The Hasty Generalization Fallacy. …
  • 6) The Slothful Induction Fallacy. …
  • 7) The Correlation/Causation Fallacy. …
  • 8) The Anecdotal Evidence Fallacy.

What is the problem with fallacy?

They may result from innocent errors in reasoning, or be used deliberately to mislead others. Taking logical fallacies at face value can lead you to make poor decisions based on unsound arguments. And using them yourself – even by mistake – can make you appear untrustworthy and damage your reputation.

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How do you tell if an argument is a fallacy?

Bad proofs, wrong number of choices, or a disconnect between the proof and conclusion. To spot logical fallacies, look for bad proof, the wrong number of choices, or a disconnect between the proof and the conclusion. Identify bad proofs. A bad proof can be a false comparison.

Is ought a claim?

The is-ought fallacy occurs when the assumption is made that because things are a certain way, they should be that way. It can also consist of the assumption that because something is not now occurring, this means it should not occur.

Can IF THEN statements be arguments?

If–then arguments , also known as conditional arguments or hypothetical syllogisms, are the workhorses of deductive logic. They make up a loosely defined family of deductive arguments that have an if–then statement —that is, a conditional—as a premise.

How do you argue against a fallacy?

To counter the use of a logical fallacy, you should first identify the flaw in reasoning that it contains, and then point it out and explain why it’s a problem, or provide a strong opposing argument that counters it implicitly.

What are the 4 types of reasoning?

Four types of reasoning will be our focus here: deductive reasoning, inductive reasoning, abductive reasoning and reasoning by analogy.

Do all Uncogent arguments commit a fallacy?

If an inductive argument commits a fallacy, then it is an uncogent argument. If an inductive argument has false premises, then it is an uncogent argument. Some uncogent arguments commit a formal fallacy. No uncogent arguments commit a formal fallacy.

Can a fallacious argument be valid?

Deductive reasoning that is incorrect (logically faulty, illogical) is fallacious. Reasoning can be valid even if the assumptions on which it is based are false. If reasoning is valid and based on true premises, it is sound. Many deductive and inductive arguments rely on statistical evidence.

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What is rejecting an idea because of where it comes from fallacy?

From Wikipedia, the free encyclopedia. The genetic fallacy (also known as the fallacy of origins or fallacy of virtue) is a fallacy of irrelevance that is based solely on someone’s or something’s history, origin, or source rather than its current meaning or context.

Do all defective arguments have false premises?

Some defective arguments do not have false premises. All arguments with false premises are either unsound or uncogent. Fallacious arguments never have false premises. Arguments that commit a formal fallacy can sometimes be made into valid arguments by rearranging the letters that are used in the argument’s form.

What makes an argument valid?

An argument is valid if the premises and conclusion are related to each other in the right way so that if the premises were true, then the conclusion would have to be true as well.

Could there be a valid argument that has one false premise and one true premise?

TRUE: A valid argument cannot have all true premises and a false conclusion. So if a valid argument does have a false conclusion, it cannot have all true premises. Thus at least one premise must be false.