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LSAT Logical Reasoning cheat sheet
The 17 types of LR questions on the LSAT
Logical Reasoning makes up two thirds of your LSAT score, and success comes from recognizing the question types. This cheat sheet breaks down the 17 types of LR questions, explains the common traps, and shows you the strategies that work. Use it to spot patterns quickly, avoid mistakes, and sharpen your reasoning skills.
Argument part
Evaluate
Flaw or descriptive weakening
Main conclusion or main point
Method of reasoning or descriptive
Most strongly supported
Must be true
Necessary assumption
Parallel flawed method of reasoning
Parallel method of reasoning
Point at issue: disagree
PSA - find or complete the application
PSA - find the rule
Resolve reconcile or explain
Strengthen
Sufficient assumption
Weaken
Argument part
Avg. 2.3 per section
Which one of the following most accurately states the role played by the statement ...
Correct answer criteria
- Accurate description of the role played by the statement we're asked about.
Key tactics
- Read the stimulus and identify the conclusion and the premises. Don't pay attention to the statement that you're asked about until you've broken down the argument first
- After breaking down the argument, think about the role of the statement you're asked about
- Is it part of the author's argument? If so, is it premise, intermediate conclusion, or main conclusion?
- If it's not part of the author's argument, is it part of someone else's argument? Is it a point of concession? Something else?
Answer choice tips
- Be careful about answers that are extreme or twist what the argument actually says - often wrong answers will just misdescribe the conclusion
- Wrong answers often describe other parts of the stimulus that aren't the statement we're asked about
- Be ready to go slow on the answers - they are often abstract and you need some time to break them down
Evaluate
Avg. 0.2 per section
The answer to which one of the following questions most helps in evaluating the argument?
Correct answer criteria
- A question that, depending on how it's answered, would either strengthen or weaken the argument.
Key tactics
- Follow the same approach as for strengthen/weaken questions
Answer choice tips
- The answers are usually phrased in the form of a question (e.g., "How often did the mayor meet with the contractor?")
- Think about what would happen to the argument if you answered the question in the most extreme way in one direction, and then the most extreme way in the opposite direction. (e.g., If the mayor met with the contractor extremely often.... and if the mayor never met with the contractor?)
Flaw or descriptive weakening
Avg. 7.7 per section
The argument is most vulnerable to criticism on the grounds that it
Correct answer criteria
- Accurate description of why the argument's reasoning is flawed. The answer could be phrased in the following ways: 1. Abstract description of the bad reasoning 2. What the argument overlooks 3. What the argument assumes
Key tactics
- Identify the conclusion and the premises
- Think about why the conclusion doesn't have to be true even if the premises are true
- Sometimes you'll be able to recognize a common form of flaw (confusing sufficient and necessary conditions, correlation to cause, etc.)
Answer choice tips
- Be careful about answers that misdescribe the conclusion
- Correct answers must be (1) descriptively accurate, and (2) constitute bad reasoning
- Answers phrased in the form of what the argument overlooks can be analyzed just like Weaken answers. (So the tendencies that apply to Weaken answers apply to these answers, too!)
- Answers phrased in the form of what the argument assumes can be analyzed just like Necessary Assumption answers. (So the tendences that apply to Necessary Assumption answers apply to these answers, too!)
Main conclusion or main point
Avg. 2.6 per section
Which one of the following most accurately expresses the main conclusion drawn in the argument?
Correct answer criteria
- Restatement or paraphrase of the main conclusion of the argument.
Key tactics
- Read the stimulus carefully and identify the main conclusion of the argument
- Usually you can tell what the main conclusion is by looking for an expression of opinion that is supported by other statements
- Often the conclusion will be phrased as a rejection of something else "That belief is false." If so, make sure to translate that statement into a full idea - what does the author mean by "that belief is false"?
- If stuck between two answers, ask which one supports the other? The one that is supported is more likely to be the correct answer
Answer choice tips
- Correct answer will be a restatement of the main conclusion, although it may not be worded in exactly the same way
- Wrong answers will often take the conclusion too far, describe a premise or assumption, or describe an inference we can make from the stimulus
Method of reasoning or descriptive
Avg. 1.1 per section
Which of the following most accurately describes a technique of reasoning used in the argument above?
Correct answer criteria
- Accurate description of the way the argument goes from premise to conclusion.
Key tactics
- Read the stimulus and identify the conclusion and the premises
- Can you recognize a common form of reasoning? (rule-application, phenomenon-hypothesis, generalization, analogy, cost/benefit, etc.)
- If you can't, that's OK; not every argument uses an easy-to-describe form of reasoning
Answer choice tips
- Be careful about answers that are extreme - wrong answers will often go beyond what the argument actually said (e.g., The second speaker said the first speaker's conclusion was "unjustified," but a wrong answer says the second speaker called the first speaker's conclusion "false.")
- Be prepared for abstract answers - you may need to take time to match different parts of the correct answer to the stimulus. If you can't match part of the answer to the stimulus, it's wrong
Most strongly supported
Avg. 4.3 per section
Which one of the following is most strongly supported by the information above?
Correct answer criteria
- Very strongly supported by the information in the stimulus - it might not be 100% proven, but you have good reasons from the stimulus to believe that the answer is true.
Key tactics
- Take statements in the stimulus as true
- There is no need to identify conclusions and premises. If the stimulus does have an argument, it can be helpful to identify any assumptions made by the argument
- If there are any statements that can be connected to each other, try to connect them
Answer choice tips
- Be careful about picking extreme answers (e.g., "All..." "Every..." "always"). Although strong answers can be OK, particularly if the stimulus is conditional-based, you should double-check to make sure they are truly supported
- Weak answers (e.g., "Sometimes..." "possibly" "not always") are more likely to be correct than strong answers, since they are easier to support
- Answers introducing concepts not discussed in the stimulus are highly unlikely to be correct
Must be true
Avg. 2.0 per section
If all of the statements above are true, which of the following can be properly inferred?
Correct answer criteria
- 100% proven by the information in the stimulus. The correct answer should not require any assumptions in order to be proven by the stimulus.
Key tactics
- Take statements in the stimulus as true
- There is no need to identify conclusions and premises
- If there are any statements that can be connected to each other, try to connect them
Answer choice tips
- Be careful about picking extreme answers (e.g., "All..." "Every..." "always"). Although strong answers can be OK, particularly if the stimulus is conditional-based, you should double-check to make sure they are truly supported
- Weak answers (e.g., "Sometimes..." "possibly" "not always") are more likely to be correct than strong answers, since they are easier to support
- Answers introducing concepts not discussed in the stimulus are highly unlikely to be correct
Necessary assumption
Avg. 4.5 per section
Which one of the following is an assumption that the argument above requires?
Logical Reasoning: Theory - Part 1 (NA)
Logical Reasoning: Theory - Part 2 (NA)
Logical Reasoning: Approach (NA)
Correct answer criteria
- Something that must be true in order for the argument's conclusion to possibly follow from the premises.
Key tactics
- Identify the conclusion and the premises
- Think about why the conclusion doesn't have to be true even if the premises are true
- Pay attention to new concepts brought up on the conclusion but not mentioned in the stimulus. The argument has to make some kind of assumption about those new ideas
- Be open-minded; sometimes an argument can have many different necessary assumptions and it's hard to predict what the correct answer will be about
- If you're uncertain about an answer, apply the negation test. Does the negation of the answer make it impossible for the conclusion to follow logically from the premises? If yes, then this answer is necessary and is correct
Answer choice tips
- Be careful about extreme answers, since they often go beyond what the argument needs to make sense. Strongly worded answers can be correct, but be careful about them
- Weak answers (e.g., "Some" "sometimes" "not always") are more likely to be correct than strong answers. When using the negation test, negating a weak statement ("some") always produces a strong statement ("none"), and strong statements are more likely to damage the conclusion
Parallel flawed method of reasoning
Avg. 2.0 per section
The flawed reasoning in which one of the following is most closely parallel to the flawed reasoning in the argument above?
Correct answer criteria
- An argument that most closely matches the flawed reasoning in the argument in the stimulus.
Key tactics
- Identify the conclusion and premises
- Try to identify why the argument is flawed - why doesn't the conclusion follow from the premises?
- Try to summarize the key elements of the premises and conclusion that you're looking to match in the correct answer
- Be ready to for conditional logic, which is common on these questions
- Pay attention to the strength of language in the conclusion
Answer choice tips
- Remember that the correct answer is supposed to have the same flaw. So if the answer's argument is valid, it's not going to be correct
- If you're stuck on an answer, make sure to check whether the strength of the conclusion matches what we're looking for. (e.g., If the answer choice conclusion says "X will probably occur" but the stimulus conclusion said "X will occur" then this doesn't match and the answer is unlikely to be correct.) There are notable exceptions to this for Parallel Flaw questions, but eliminating based on strength of conclusion is still a good general rule of thumb
Parallel method of reasoning
Avg. 2.0 per section
The reasoning in the argument above is most similar to the reasoning in which one of the following arguments?
Correct answer criteria
- An argument that most closely matches the key elements of reasoning in the argument in the stimulus.
Key tactics
- Identify the conclusion and premises
- Try to summarize the key elements of the premises and conclusion that you're looking to match in the correct answer
- Be ready to for conditional logic, which is common on these questions
- Pay attention to the strength of language in the conclusion
Answer choice tips
- If you're stuck on an answer, make sure to check whether the strength of the conclusion matches what we're looking for. (e.g., If the answer choice conclusion says "X will probably occur" but the stimulus conclusion said "X will occur" then this doesn't match and the answer is unlikely to be correct.)
- Make sure to evaluate the answers sentence by sentence. Often you don't need to read the whole answer to see that there are parts of it that don't match
Point at issue: disagree
Avg. 1.9 per section
These statements commit Robin and Kendall to disagreeing over whether
Correct answer criteria
- A statement that one speaker would say "Yes" to and the other speaker would say "No" to.
Key tactics
- Break down the first person's statement
- Then, break down the second person's
- Think about whether they disagree about a conclusion, premise, assumption, or something else
Answer choice tips
- Does each person have an opinion on the answer? If not, or you don't know, then it's wrong
- The correct answer is one for which each speaker has an opinion and those opinions conflict. One person says "Yes" to the answer and the other person says "No."
PSA - find or complete the application
Avg. 0.9 per section
Which one of the following judgments most closely conforms to the principle above?
Correct answer criteria
- An argument or situation that matches one of the principles in the stimulus.
Key tactics
- Understand the principle in the stimulus
- Often the principle will involve conditional logic. Be ready to break down the principle into "if" and "then"
- You may need to think about the contrapositive of the principle
Answer choice tips
- Common wrong answers will involve a reversal of the conditional logic
- If you're stuck, make sure to identify the answer's conclusion and premises, and then see whether each part of the argument fits the principle. The conclusion should match up to the "then" part and the premises should match up to the "if" part
PSA - find the rule
Avg. 2.7 per section
Which one of the following principles, if valid, would most help to justify the argument?
Correct answer criteria
- Something that, if true, would make the conclusion more likely to follow from the premises.
Key tactics
- Identify the conclusion and the premises
- Identify a "premise -> conclusion" bridge
Answer choice tips
- The correct answer doesn't need to 100% prove the conclusion. It just need provide a principle that would make the conclusion more likely to follow from the premises
- Be ready to think about contrapositives - the correct answer is often presented in this form
Resolve reconcile or explain
Avg. 3.6 per section
Which one of the following, if true, most helps to resolve the apparent discrepancy in the information above?
Correct answer criteria
- Something that, if true, would help explain the apparently conflicting facts in the stimulus.
Key tactics
- Usually the stimulus involves an apparent contradiction or conflict
- Try to identify the two things that seem to conflict - why don't these seem to go together?
Answer choice tips
- The correct answer just needs to help provide a potential explanation that resolves the discrepancy. It's OK for the correct answer to require a small, reasonable assumption
- Wrong answers will either be irrelevant or make the discrepancy more difficult to explain
Strengthen
Avg. 3.9 per section
The conclusion of the argument is strongly supported if which one of the following is assumed?
Logical Reasoning: Transition to Strengthen (S)
Logical Reasoning: Theory and Approach (WSE Non-Causal)
Correct answer criteria
- Something that, if true, would make the conclusion more likely to follow from the premises.
Key tactics
- Identify the conclusion and the premises
- Think about why the conclusion doesn't have to be true even if the premises are true
- Pay attention to new concepts brought up on the conclusion but not mentioned in the stimulus. The argument has to make some kind of assumption about those new ideas
- Be ready for arguments where the author tries to provide a hypothesis (causal explanation) for some phenomenon. If you see this structure, think about alternate hypotheses
- Be open-minded. It's had to predict exactly what the correct answer will involve
Answer choice tips
- The correct answer doesn't need to 100% prove the conclusion. Even if it just makes the conclusion slightly more likely to follow from the premises, it can still be considered a strengthen answer. If multiple answers appear to strengthen, choose the answer that most strengthens (the answer that requires the fewest, and most reasonable assumptions)
- If the argument involves correlation to cause or explanations for a phenomenon, be ready for a correct answer that is about eliminating an alternate explanation. This isn't always the correct answer, but it's common on this kind of argument
Sufficient assumption
Avg. 3.0 per section
The conclusion of the argument follows logically if which one of the following is assumed?
Correct answer criteria
- Something that, if added to the premises, would 100% guarantee the truth of the conclusion.
Key tactics
- Identify the conclusion and the premises
- Think about why the conclusion doesn't have to be true even if the premises are true
- Pay attention to new concepts brought up in the conclusion but not mentioned in the stimulus. The argument has to make some kind of assumption about those new ideas
- Be ready for conditional logic in the premises or conclusion. Sufficient assumption questions often involve identifying missing links between different conditional relationships
- If you're stuck on an answer, ask whether that answer, combined with the premises, 100% proves the conclusion. If it doesn't, it's not correct
Answer choice tips
- Be careful about picking weak answers. It's difficult for a weakly worded answer to guarantee the truth of the conclusion
- Be ready to think about contrapositives - sometimes you may know what you're looking for but the correct answer is presented in the contrapositive form
Weaken
Avg. 5.2 per section
Which of the following, if true, most weakens the argument?
Correct answer criteria
- Something that, if true, would make the conclusion less likely to follow from the premises.
Key tactics
- Identify the conclusion and the premises
- Think about why the conclusion doesn't have to be true even if the premises are true
- Pay attention to new concepts brought up on the conclusion but not mentioned in the stimulus. The argument has to make some kind of assumption about those new ideas
- Be ready for arguments where the author tries to provide a hypothesis (causal explanation) for some phenomenon. If you see this structure, think about alternate hypotheses
- Be open-minded. It's had to predict exactly what the correct answer will involve
Answer choice tips
- The correct answer doesn't need to falsify the conclusion - even if it just makes the conclusion slightly less likely to follow from the premises, it can still be correct. If multiple answers appear to weaken, choose the answer that most weakens (the answer that requires the fewest, and most reasonable assumptions)
- If the argument involves correlation to cause or explanations for a phenomenon, be ready for a correct answer that is about providing an alternate explanation. This isn't always the correct answer, but it's common on this kind of argument