Apply the Principle - LSAT Logical Reasoning
Card 1 of 30
Identify the flaw: Using $A \rightarrow B$ and $\neg A$ to conclude $\neg B$ is what error?
Identify the flaw: Using $A \rightarrow B$ and $\neg A$ to conclude $\neg B$ is what error?
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Denying the antecedent. This fallacy incorrectly negates without reversing.
Denying the antecedent. This fallacy incorrectly negates without reversing.
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Apply this rule: $P \rightarrow Q$. If a choice states $Q$ and concludes $P$, is it supported?
Apply this rule: $P \rightarrow Q$. If a choice states $Q$ and concludes $P$, is it supported?
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No, that is not supported (it affirms the consequent). Knowing $Q$ doesn't tell us about $P$ without additional info.
No, that is not supported (it affirms the consequent). Knowing $Q$ doesn't tell us about $P$ without additional info.
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When the principle contains an exception, what must a correct answer choice do?
When the principle contains an exception, what must a correct answer choice do?
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Satisfy the main rule and also respect the stated exception conditions. Exceptions create additional conditions that must be checked.
Satisfy the main rule and also respect the stated exception conditions. Exceptions create additional conditions that must be checked.
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What is the core task in an Apply the Principle question?
What is the core task in an Apply the Principle question?
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Select the option that best conforms to the stated principle. Match answer choices to the given general rule.
Select the option that best conforms to the stated principle. Match answer choices to the given general rule.
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What is the difference between a principle and a premise in the stimulus?
What is the difference between a principle and a premise in the stimulus?
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A principle is a general rule; a premise is a case-specific fact. Principles apply broadly; premises describe specific situations.
A principle is a general rule; a premise is a case-specific fact. Principles apply broadly; premises describe specific situations.
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What is the key structural feature of a principle that uses “unless”?
What is the key structural feature of a principle that uses “unless”?
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“Unless” marks an exception; translate to a conditional with a negation. "Unless" means "if not," requiring conditional translation.
“Unless” marks an exception; translate to a conditional with a negation. "Unless" means "if not," requiring conditional translation.
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What is the most reliable way to represent a principle for matching purposes?
What is the most reliable way to represent a principle for matching purposes?
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Rewrite as an if–then rule with clear sufficient and necessary parts. Conditionals clarify when the principle applies.
Rewrite as an if–then rule with clear sufficient and necessary parts. Conditionals clarify when the principle applies.
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Which direction of fit is required when the question asks for an action most consistent with the principle?
Which direction of fit is required when the question asks for an action most consistent with the principle?
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Choice must be an instance that satisfies the principle’s conditions. The choice must meet all conditions stated in the principle.
Choice must be an instance that satisfies the principle’s conditions. The choice must meet all conditions stated in the principle.
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Which direction of fit is required when the question asks for a principle that justifies the conclusion?
Which direction of fit is required when the question asks for a principle that justifies the conclusion?
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Principle must make the conclusion follow from the facts. The principle must logically connect facts to conclusion.
Principle must make the conclusion follow from the facts. The principle must logically connect facts to conclusion.
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Which option matches the principle “If an act risks harm, it is impermissible” for an act that risks harm?
Which option matches the principle “If an act risks harm, it is impermissible” for an act that risks harm?
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The option concluding the act is impermissible. The act meets the sufficient condition for impermissibility.
The option concluding the act is impermissible. The act meets the sufficient condition for impermissibility.
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What is the contrapositive of $A \rightarrow B$?
What is the contrapositive of $A \rightarrow B$?
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$\neg B \rightarrow \neg A$. Contrapositive switches and negates both parts.
$\neg B \rightarrow \neg A$. Contrapositive switches and negates both parts.
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Which inference is valid from $A \rightarrow B$ and $\neg B$?
Which inference is valid from $A \rightarrow B$ and $\neg B$?
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$\neg A$. Modus tollens: denying the consequent denies the antecedent.
$\neg A$. Modus tollens: denying the consequent denies the antecedent.
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Which inference is valid from $A \rightarrow B$ and $A$?
Which inference is valid from $A \rightarrow B$ and $A$?
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$B$. Modus ponens: affirming the antecedent yields the consequent.
$B$. Modus ponens: affirming the antecedent yields the consequent.
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Identify the correct conditional form: “A only if not B.”
Identify the correct conditional form: “A only if not B.”
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$A \rightarrow \neg B$. Combines "only if" with negation.
$A \rightarrow \neg B$. Combines "only if" with negation.
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Identify the correct conditional form: “A unless B.”
Identify the correct conditional form: “A unless B.”
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$\neg B \rightarrow A$. "Unless" means if not B, then A.
$\neg B \rightarrow A$. "Unless" means if not B, then A.
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Identify the correct conditional form: “A if B.”
Identify the correct conditional form: “A if B.”
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$B \rightarrow A$. "If" makes B sufficient for A.
$B \rightarrow A$. "If" makes B sufficient for A.
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Identify the correct conditional form: “A only if B.”
Identify the correct conditional form: “A only if B.”
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$A \rightarrow B$. "Only if" makes B necessary for A.
$A \rightarrow B$. "Only if" makes B necessary for A.
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Identify the correct conditional form: “No A are B.”
Identify the correct conditional form: “No A are B.”
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$A \rightarrow \neg B$. "No" means if A, then not B.
$A \rightarrow \neg B$. "No" means if A, then not B.
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Identify the correct conditional form: “All A are B.”
Identify the correct conditional form: “All A are B.”
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$A \rightarrow B$. "All" creates a conditional: if A, then B.
$A \rightarrow B$. "All" creates a conditional: if A, then B.
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In Apply the Principle, what does “most strongly supported” typically require?
In Apply the Principle, what does “most strongly supported” typically require?
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The choice best fits the principle; perfect proof is not required. Choose the option that aligns best with the principle.
The choice best fits the principle; perfect proof is not required. Choose the option that aligns best with the principle.
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What is the most common wrong-answer pattern in Apply the Principle questions?
What is the most common wrong-answer pattern in Apply the Principle questions?
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A choice that matches topic words but not the rule’s logical structure. Surface similarity without logical match is a common trap.
A choice that matches topic words but not the rule’s logical structure. Surface similarity without logical match is a common trap.
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When a principle includes an exception clause, what must the correct choice do?
When a principle includes an exception clause, what must the correct choice do?
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Satisfy the rule and not trigger the exception. Must follow the main rule while avoiding exception conditions.
Satisfy the rule and not trigger the exception. Must follow the main rule while avoiding exception conditions.
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What is the key structural feature of a principle that uses “only if”?
What is the key structural feature of a principle that uses “only if”?
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“Only if” introduces a necessary condition. What follows "only if" must occur for the first part to be true.
“Only if” introduces a necessary condition. What follows "only if" must occur for the first part to be true.
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Apply this rule: $P \rightarrow Q$. If a choice states $P$ and concludes $Q$, is it consistent?
Apply this rule: $P \rightarrow Q$. If a choice states $P$ and concludes $Q$, is it consistent?
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Yes, it is a valid application of $P \rightarrow Q$. This follows modus ponens: affirming the antecedent.
Yes, it is a valid application of $P \rightarrow Q$. This follows modus ponens: affirming the antecedent.
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What is the correct contrapositive of $A \rightarrow B$?
What is the correct contrapositive of $A \rightarrow B$?
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$\neg B \rightarrow \neg A$. The contrapositive reverses and negates both parts.
$\neg B \rightarrow \neg A$. The contrapositive reverses and negates both parts.
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What is the most common wrong-answer type in Apply the Principle questions?
What is the most common wrong-answer type in Apply the Principle questions?
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It reverses or negates the rule (confuses sufficient and necessary conditions). This error treats necessary conditions as sufficient.
It reverses or negates the rule (confuses sufficient and necessary conditions). This error treats necessary conditions as sufficient.
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Which option is correct: In Apply the Principle, you should match surface details or structure?
Which option is correct: In Apply the Principle, you should match surface details or structure?
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Structure (the rule’s conditions and conclusion), not surface topic. Focus on logical form, not content similarity.
Structure (the rule’s conditions and conclusion), not surface topic. Focus on logical form, not content similarity.
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What does it mean for an answer choice to be “parallel in principle” to the stimulus?
What does it mean for an answer choice to be “parallel in principle” to the stimulus?
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It matches the same rule-trigger and the same permitted/required outcome. Parallel principles share the same logical structure and outcome type.
It matches the same rule-trigger and the same permitted/required outcome. Parallel principles share the same logical structure and outcome type.
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Identify the conditional translation: “Unless A, B.” Which form is correct?
Identify the conditional translation: “Unless A, B.” Which form is correct?
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$\neg A \rightarrow B$. "Unless" means "if not," so not having A is sufficient for B.
$\neg A \rightarrow B$. "Unless" means "if not," so not having A is sufficient for B.
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Identify the conditional translation: “A if B.” Which form is correct?
Identify the conditional translation: “A if B.” Which form is correct?
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$B \rightarrow A$. "If" introduces a sufficient condition, so B is sufficient for A.
$B \rightarrow A$. "If" introduces a sufficient condition, so B is sufficient for A.
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