Chapter 5 Fallacies That Violate the Structural Criterion

Structural Fallacies in Argumentation

To be a well-formed argument, reasoning must follow proper logical structure. A structurally flawed argument:

• Contradicts itself or the conclusion.
• Assumes the truth of the conclusion within the premises.
• Violates rules of deductive logic or draws invalid inferences.
• Fails to provide real reasons to accept the conclusion.

Types of Structural Fallacies

1. Begging-the-Question Fallacies

• Definition: Assume the truth of the conclusion within the premises.
• Flaw: Premises do not provide independent support for the conclusion.
• Example:
  • “God exists because the Bible says so, and the Bible is true because God wrote it.” (Circular reasoning)

2. Fallacies of Inconsistency

• Definition: Use contradictory premises or draw a conclusion that contradicts a premise.
• Flaw: Contradictions prevent the argument from having a coherent foundation.
• Example:
  • “I am in favor of free speech, but people who criticize the government should be punished.”

3. Fallacies of Deductive Inference

• Definition: Violate formal rules of deductive logic, leading to invalid reasoning.
• Flaw: Even if the premises are true, the conclusion does not logically follow.
• Examples:
  • Denying the Antecedent:
    • “If it rains, the ground is wet. It is not raining, so the ground is not wet.” (Ignores other possible causes of wet ground)
  • Affirming the Consequent:
    • “If I have the flu, I have a fever. I have a fever, so I must have the flu.” (Ignores other possible causes of a fever)

Key Takeaways

• Structural fallacies make arguments fundamentally unreliable—even if the premises seem valid.
• Flaws exist regardless of content—they remain illogical even when symbols replace words.
• A good argument must be structurally sound, ensuring its conclusion logically follows from its premises.

Begging-the-Question Fallacies

These fallacies occur when an argument assumes the truth of its conclusion in its premises. Instead of providing independent support for the conclusion, the argument circularly reinforces itself, violating the structural principle of a good argument.

Types of Begging-the-Question Fallacies

1. Arguing in a Circle

• Definition: The premise simply restates the conclusion in different words.
• Flaw: No actual reasoning is provided; the argument assumes what it sets out to prove.
• Example:
  • “Reading is enjoyable because it is fun.”
  • “God exists because I don’t want to go to hell.” (Assumes hell exists and that God sends people there.)
• How to Attack It:
  • Identify the circular reasoning by restating the premise and conclusion side by side.
  • Ask the arguer to provide independent evidence rather than repeating the conclusion.
  • Use an absurd counterexample to expose the flaw (e.g., “Candy is healthy because it’s good for you.”).

2. Question-Begging Language

• Definition: The arguer frames the discussion in a way that assumes a conclusion without proving it.
• Flaw: Subtly directs the audience toward the intended conclusion without actual evidence.
• Example:
  • “Since I was cheated, you should conclude that I was cheated.” (Assumes the key point in dispute.)
  • “Obviously, no intelligent person would oppose this bill.” (Uses loaded language to silence disagreement.)
  • “You aren’t really considering voting for that clown, are you?” (Uses prejudicial phrasing to dismiss opposition.)
• How to Attack It:
  • Point out the biased or loaded language and ask the speaker to restate the argument neutrally.
  • Question the implicit assumption that has been unfairly included in the argument.
  • If confronted with leading questions, refuse to accept the assumed premise and request clarification.

3. Complex Question

• Definition: The question assumes an answer to an unstated question that remains open for debate.
• Flaw: The respondent cannot answer without granting a controversial assumption.
• Example:
  • “What did you do with my watch after you stole it?” (Assumes theft occurred.)
  • “When are you going to settle down and get married?” (Assumes marriage is inevitable.)
  • “Are you and Nancy going to the wedding and the reception, even though you weren’t invited?” (Bundles separate questions together, forcing a misleading yes/no answer.)
• How to Attack It:
  • Refuse to answer in a simple “yes” or “no”—insist on clarifying the assumptions.
  • Break the question down into its separate components to respond accurately.
  • Point out that the issue is still open and requires discussion, not assumption.

4. Question-Begging Definition

• Definition: A key term is defined in a way that guarantees the argument’s conclusion.
• Flaw: The definition prevents counterevidence from being considered, making the argument true by definition rather than by factual support.
• Example:
  • “True Christians don’t drink alcohol.” (Defines “Christian” in a way that excludes counterexamples.)
  • “Real love never ends in divorce.” (Rejects counterexamples by defining “true love” in an unfalsifiable way.)
  • “A ‘true-blue’ Republican would never switch parties.” (Ignores real-world cases of party-switching.)
• How to Attack It:
  • Ask whether the premise is empirical (fact-based) or definitional.
  • Request examples of evidence that would count against the definition—if none are allowed, expose the circularity.
  • Compare the definition to common usage or expert opinions (e.g., dictionary definitions).

Key Takeaways

• Begging-the-question fallacies give the illusion of reasoning without actual support.
• Arguments must use premises that are truly independent from the conclusion.
• Detecting and challenging assumptions in language and definitions prevents faulty reasoning from misleading the discussion.

Fallacies of Inconsistency

These fallacies occur when an argument contains contradictions, either between premises or between a premise and the conclusion. Because contradictions violate the law of noncontradiction (not both A and not-A), arguments containing them are structurally flawed and cannot lead to a valid conclusion.

Types of Inconsistency Fallacies

1. Incompatible Premises

• Definition: An argument that draws a conclusion from premises that contradict each other.
• Flaw: Since at least one premise must be false, no valid conclusion can be drawn.
• Logical Form:
  • Since A, (premise)
  • And not-A, (premise)
  • [No valid conclusion can be drawn.]

Examples

• The Problem of Evil

  • “If God is all-knowing, all-powerful, and perfectly good, then there would be no evil. But evil exists.”
  • This presents incompatible premises—either God does not have all these attributes or evil does not exist (which contradicts observation).

• Divine Command Theory

  • “An act is right because God says so. But God would never command certain acts (e.g., rape, murder) because they are wrong.”
  • This contradicts itself: If morality is based only on God’s command, then nothing is inherently wrong. If some acts are inherently wrong, morality cannot depend solely on God’s command.

• Political Contradictions

  • “I will lower taxes and maintain (or expand) all government services.”
  • These claims conflict unless the politician identifies new revenue sources or cuts spending elsewhere.

How to Attack It

• Restate the contradiction explicitly using A and not-A format.
• Ask the arguer to choose which premise they wish to keep.
• Show that no valid conclusion can follow unless the contradiction is resolved.

2. Contradiction Between Premise and Conclusion

• Definition: An argument that draws a conclusion that contradicts one of its premises.
• Flaw: The conclusion directly denies an assumption used to justify it.
• Logical Form:
  • Since A, (premise)
  • And B, (premise)
  • Therefore, not-A. (conclusion)
  • (A and not-A cannot both be true.)

Examples

• The First Cause Argument (Cosmological Argument for God’s Existence)

  • “Everything has a cause. Therefore, there must be an uncaused first cause (God).”
  • This contradicts itself: If everything has a cause, then God must also have a cause. If God is uncaused, then not everything has a cause, contradicting the first premise.

• Dualism and the Mind-Body Problem (René Descartes)

  • “The body is physical and occupies space. The mind is nonphysical and does not occupy space. But the mind and body interact.”
  • Contradiction: If the mind does not occupy space, how can it interact with the physical world?

• Abortion and Exceptions for Rape

  • “All human life is sacred and must be protected. Abortion is wrong because it destroys human life. However, abortion is acceptable in cases of rape.”
  • If all human life is sacred, then the exception for rape contradicts the principle. Either:
    • The first premise must be weakened (not all life is equally sacred).
    • The exception must be removed.

How to Attack It

• Restate the contradiction explicitly using A and not-A format.
• Ask the arguer to explain how both the premise and conclusion can be true at the same time.
• Challenge them to modify their argument so that it does not contradict itself.

Key Takeaways

• Contradictions make arguments structurally invalid—they violate the law of noncontradiction.
• Arguments with incompatible premises cannot reach a valid conclusion.
• Arguments where the conclusion contradicts a premise must be revised before they can be accepted.
• Attacking these fallacies involves identifying contradictions explicitly and demanding resolution.

Fallacies of Deductive Inference

Fallacies of deductive inference violate fundamental rules of deductive reasoning. These fallacies result in arguments that appear logical but do not follow valid reasoning structures.

1. Denying the Antecedent

• Definition: An argument denies the antecedent (A) of a conditional statement (If A, then B) and incorrectly denies the consequent (not B).
• Logical Form:
  • If A, then B (premise)
  • Not A (premise)
  • Therefore, not B (conclusion)
• Flaw: The arguer assumes that A is the only reason for B, ignoring other possible causes of B.

Examples

• “If I were a heavy smoker, my life would be shortened. I don’t smoke, so I’ll live a long life.”
  • Flaw: Other factors (e.g., genetics, diet) can also shorten life.
• “If capital punishment deterred crime, it would be justified. But it doesn’t deter crime, so it’s unjustified.”
  • Flaw: Other reasons (e.g., justice, retribution) might justify capital punishment.
• “If I pass the final, I will pass the course. I didn’t pass the final, so I failed the course.”
  • Flaw: Other factors (assignments, participation, extra credit) could allow passing.

Attacking the Fallacy

• Use an absurd counterexample:
  • “If Newt is a dog, then Newt is an animal. Newt is not a dog, so Newt is not an animal.”
  • Flaw: Newt could be a cat, which is also an animal.

2. Affirming the Consequent

• Definition: An argument affirms the consequent (B) of a conditional statement (If A, then B) and incorrectly infers A.
• Logical Form:
  • If A, then B (premise)
  • B (premise)
  • Therefore, A (conclusion)
• Flaw: The arguer assumes A is the only cause of B, ignoring other possible causes.

Examples

• “If a husband plans to murder his wife, he will take out a life insurance policy. He took out a life insurance policy, so he must be planning to murder her.”
  • Flaw: Other reasons (e.g., financial planning) exist for buying life insurance.
• “If you do well on the SAT, you’ll get into a good college. You got into a good college, so you must have done well on the SAT.”
  • Flaw: Other factors (e.g., grades, sports, extracurriculars) could help admission.
• “If I eat red meat, I get sick. I got sick, so I must have eaten red meat.”
  • Flaw: Other causes (e.g., food poisoning) could explain the illness.

Attacking the Fallacy

• Use an absurd counterexample:
  • “If someone is the president, they must be at least 35 years old and a U.S. citizen. You are at least 35 and a U.S. citizen, so you must be the president.”
  • Flaw: Many non-presidents also meet these criteria.

3. False Conversion

• Definition: An argument incorrectly reverses the terms of a conditional statement (If A, then B → If B, then A) or an “all X are Y” statement.
• Logical Form:
  • If A, then B → If B, then A
  • All X are Y → All Y are X
• Flaw: The arguer assumes B cannot occur without A, even though other conditions can also lead to B.

Examples

• “All heroin addicts started by smoking marijuana. Therefore, all marijuana smokers will become heroin addicts.”
  • Flaw: Many marijuana smokers do not become heroin addicts.
• “If you are a Christian, you love and care for others. Therefore, if you love and care for others, you must be a Christian.”
  • Flaw: Many non-Christians also care for others.

Attacking the Fallacy

• Use an absurd counterexample:
  • “All apples are fruits. Therefore, all fruits are apples.”
  • Flaw: Bananas, oranges, and grapes are also fruits.

4. Undistributed Middle Term

• Definition: A syllogism draws a conclusion without ensuring that the middle term links both premises.
• Logical Form:
  • All A are B (premise)
  • All C are B (premise)
  • Therefore, all C are A (invalid conclusion)
• Flaw: The middle term is not fully connected to both premises.

Examples

• “Some philosophers are poor discussion leaders. Some of our professors are philosophers. Therefore, some of our professors are poor discussion leaders.”
  • Flaw: Not all philosophers are poor discussion leaders, and not all professors are philosophers.
• “Democrats care about helping the least advantaged. Jesus cared about helping the least advantaged. Therefore, Jesus was a Democrat.”
  • Flaw: Others (Republicans, Independents, non-political people) also care for the disadvantaged.

Attacking the Fallacy

• Use an absurd counterexample:
  • “Professors read books. Children read books. Therefore, professors are children.”
  • Flaw: The two groups share a characteristic but are not identical.

5. Illicit Distribution of an End Term

• Definition: A term in the conclusion is distributed (applies to all members of a category) but was not distributed in the premises.
• Flaw: The conclusion overgeneralizes from the premises.

Examples

• “Everything morally right is just. Some actions that bring the greatest good are not just. Therefore, some morally right actions do not bring the greatest good.”
  • Flaw: The term ‘greatest good’ is distributed in the conclusion but not in the premise.
• “Newly built homes are expensive. Newly built homes are energy-efficient. Therefore, all energy-efficient homes are expensive.”
  • Flaw: Not all energy-efficient homes are newly built.

Attacking the Fallacy

• Use an absurd counterexample:
  • “All fathers have children. No mothers are fathers. Therefore, no mothers have children.”
  • Flaw: Mothers obviously have children despite not being fathers.

Key Takeaways

• Denying the Antecedent: Wrongly assumes A is the only cause of B.
• Affirming the Consequent: Wrongly assumes B can only be caused by A.
• False Conversion: Incorrectly reverses a conditional or universal statement.
• Undistributed Middle Term: Fails to properly connect premises to the conclusion.
• Illicit Distribution of an End Term: Overgeneralizes by distributing a term in the conclusion that wasn’t distributed in the premises.

Best Attack Strategies:

• Absurd counterexamples (e.g., “All apples are fruits, therefore all fruits are apples.”).
• Pointing out other possible causes (A is not the only cause of B).
• Clarifying logical structure (Restate the argument in symbolic form).