LSAT Flaw Flashcards

Bad Conditional Reasoning

Argument misreads or reverses a conditional statement.

• Mixes up sufficient/necessary

• Common forms:

  • Affirming the consequent

  • Denying the antecedent

• 🚩 Red flag: conclusion reverses direction

• Loophole: What if the conditional chain doesn’t go both ways?

• Assumption:
  The conditional relationship works both ways (it doesn’t).

Bad Causal Reasoning

Argument assumes correlation = causation.

• Sees 2 things related → assumes one causes the other

• 🚩 Missing alternatives:

  • Third factor

  • Reverse causation

  • Coincidence

• Loophole: What if something else caused it?

• Assumption:
  No other factor explains the relationship.

Whole-to-Part / Part-to-Whole

Argument wrongly applies traits between group and members.

• Whole → Part flaw: group has trait → each member does

• Part → Whole flaw: one member has trait → whole group does

• Loophole: What if parts ≠ whole?

• Assumption:
  What’s true of one level (part/whole) is true of the other.

Overgeneralization

Conclusion about a group based on too small/specific evidence.

• Uses limited examples → broad claim

• 🚩 Keywords: “all,” “most,” “generally”

• Loophole: What if this case isn’t representative?

• Assumption:
  The example is representative of the whole group.

Survey Problems

Argument relies on flawed survey data.

• Possible issues:

  • Biased sample

  • Small sample

  • Bad questions

  • Survey errors

• Loophole: What if the survey is unreliable?

• Assumption:
  The survey accurately represents the population.

False Starts

Assumes 2 groups are the same except for one difference.

• Study compares groups

• Assumes only 1 variable differs

• 🚩 Ignores other differences

• Loophole: What if groups differ in another key way?

• Assumption:
  The groups are identical except for the tested factor.

Possibility vs. Certainty

Argument confuses “could be” with “must be.”

• Evidence suggests possibility → concludes certainty

• OR lack of proof → concludes false

• Loophole: What if it’s only possible, not guaranteed?

• Assumption:
  If something is possible, it is therefore certain.

Implication (Belief vs Fact)

Assumes believing something = believing its implication.

• Person believes X

• Argument claims they believe implication of X

• 🚩 Opinions ≠ full logical implications

• Loophole: What if they don’t accept that implication?

• Assumption:
  If someone believes X, they believe everything implied by X.

False Dichotomy (False Choice)

Presents only 2 options when more exist.

• “Either A or B”

• Eliminates one → concludes the other

• 🚩 Ignores spectrum

• Loophole: What if there’s a third option?

• Assumption:
  These are the only possible options.

Straw Man

Misrepresents someone’s argument to make it easier to attack.

• Original claim → distorted version

• Attacks the distortion

• Loophole: What if that’s not what they actually said?

• Assumption:
  The distorted version accurately represents the original claim.

Ad Hominem

Attacks the person instead of the argument.

“They’re biased → argument is false”

• 🚩 Character ≠ truth value

• Loophole: What if their argument is still valid?

• Assumption:
  If a person is flawed, their argument is false.

Circular Reasoning

Conclusion is assumed in the premises.

• Premise = restated conclusion

• 🚩 No new evidence

• Loophole: What if we remove the conclusion—any support left?

• Assumption:
  The conclusion is already true.

Equivocation

Uses a word in two different meanings.

• Same word shifts meaning mid-argument

• 🚩 Subtle definition change

• Loophole: What if the meaning stayed consistent?

• Assumption:
  The word means the same thing throughout

• Assumption:
  Opinions = valid evidence of truth.

• Assumption:
  The word means the same thing throughout.

Appeal Fallacies

Uses opinions instead of evidence.

Types:

• Authority (non-expert)

• Popular opinion (“everyone thinks…”)

• 🚩 Opinion ≠ fact

Loophole: What if that opinion is wrong?

Assumption:
Opinions = valid evidence of truth.

Irrelevant Argument

Conclusion doesn’t follow from premises.

• Premises talk about one thing

• Conclusion jumps elsewhere

• Loophole: What if they’re unrelated?

Assumption:
The premises actually support the conclusion.

Percentages vs Numbers

Confuses percentages with actual amounts.

• % increases/decreases ≠ real numbers

• 🚩 Missing base size

• Loophole: What if total size changed?

Assumption:
The total quantity stays the same.