Also Known As: Argumentum ad Logicam, Fallacist’s Fallacy
This fallacy occurs when someone infers that a claim is false because a fallacy has been used to “support” that claim. The form of this “reasoning” is as follows:
P1. Fallacy F was used to argue for claim C.
Conclusion: Therefore claim C is false.
This is a fallacy (and a somewhat ironic one) because the truth or falsity of a claim cannot be inferred solely from the quality of the reasoning. If someone has committed a fallacy, then they have made an error in reasoning but they need not have made any factual errors. As such, they have failed to provide logical support for the claim. Whether the person’s claim is true or false is an entirely different matter.
This is especially clear when a deductive fallacy (an invalid deductive argument) is considered:
P1. If Washington D.C. is the capital of the United States, then it is in the United States.
P2. Washington D.C. is in the United States.
Conclusion: Washington D.C. is the capital of the United States.
This is an example of affirming the consequent and is invalid. However, the conclusion is true. As such, it should be clear that poor reasoning does not entail a false conclusion.
Glenn: “Obama is a Muslim and a socialist. That is why he is wrong when he claims his stimulus plan helped the economy.”
Jon: “Aha! I just read about fallacies on the internet and you, my fine fellow, have just committed an ad hominem! That means that you are wrong: Obama’s plan must have helped the economy.”
Sally: “Why should you believe in God? Well, the bible says that God exists.”
Jane: “But why should I believe the bible? It is just a book after all.”
Sally: “It was written by God, so you can believe every word.”
Jane: “Hey, you are just assuming what you need to prove. That isn’t a good argument at all! So, that just about wraps it up for God.”
Sally: “Well, your argument is bad, so your conclusion has to be wrong.”
Jane: “I don’t think it works that way.”
Sally: “Why, did God put that in His book?”