Flaws: Mistaken Negation (TM)

PowerScore has trademarked a remarkable number of terms that have become standard LSAT jargon, including the term “Mistaken Negation (TM).” This logical error was identified more than two thousand years before PowerScore trademarked the name, however. Aristotle listed “denying the antecedent” as one of the thirteen original fallacies. Whatever we call this error, it shows up whenever you find this pattern:

  • If you live in Detroit, you live in Michigan
  • Therefore, if you don’t live in Detroit, you don’t live in Michigan.

This error is obvious when you use an intuitive example involving geography, but it is less obvious in other contexts. Don’t let that keep you from looking for it every chance you get–this little error is easy to slip into an argument and hard for the untrained eye to spot. That means you’ll see lots of these errors in easy-to-medium flaw questions.

You’ll see this answer choice often, but it may be the hardest answer to make sense of. The LSAT writers often use abstract terms that tend to paralyze the student. While it is possible to decode these baffling answers and demonstrate that they describe a “mistaken negation (TM),” it is very hard to do that with the clock ticking and your future on the line. That’s why it is so important to learn to identify this and other flaw answers before test day.

Here are some examples of answers that describe this particular flaw. (These are not actual LSAT answers, due to copyrights, but they are inspired by and similar to real answers):

  • “It treats a sufficient condition for an argument’s conclusion to be a necessary condition for that conclusion.”
  • “Takes a sufficient condition to be a necessary condition.”
  • “Mistakes something that is sufficient to make an argument invalid for something that is necessary to make that argument invalid.”

Basically, these answers all indicate that somebody confused a sufficient condition for a necessary condition. That sounds a lot like a “mistaken reversal (TM)” (which is what happens when you confuse a necessary condition for a sufficient condition), but it is different. If you think a condition is necessary, then not having that condition means you can’t have the other condition.  Here’s how that works out:

  • If you live in Detroit, you live in Michigan (true)
  • If you live in Michigan, you live in Detroit (false–you confused the necessary term for a sufficient term)
  • If you don’t live in Detroit, you don’t live in Michigan (false–you confused the sufficient term for a necessary term by saying what would happen if you didn’t have that term)

Flaws: Mistaken Reversal (TM)

PowerScore has trademarked a remarkable number of terms that have become standard LSAT jargon, including the term “Mistaken Reversal (TM).” This logical error was identified more than two thousand years before PowerScore trademarked the name, however. Aristotle listed “affirming the consequent” as one of the thirteen original fallacies. Whatever we call this error, it shows up whenever you find this pattern:

  • If you live in Detroit, you live in Michigan
  • Therefore, if you live in Michigan, you live in Detroit.

This error is obvious when you use an intuitive example involving geography, but it is less obvious in other contexts. Don’t let that keep you from looking for it every chance you get–this little error is easy to slip into an argument and hard for the untrained eye to spot. That means you’ll see lots of these errors in easy-to-medium flaw questions.

You’ll see this answer choice often, but it may be the hardest answer to make sense of. The LSAT writers often use abstract terms that tend to paralyze the student. While it is possible to decode these baffling answers and demonstrate that they describe a “mistaken reversal (TM),” it is very hard to do that with the clock ticking and your future on the line. That’s why it is so important to learn to identify this and other flaw answers before test day.

Here are some examples of answers that describe this particular flaw. (These are not actual LSAT answers, due to copyrights, but they are inspired by and similar to real answers):

  • “It mistakes a situation that must be present to establish the validity of the conclusion for a situation that would guarantee the validity of the conclusion.”
  • “It treats a requirement for a pig to fly as something that ensures that a pig will fly.”
  • “It takes a necessary condition for an argument’s failure to be a condition that would guarantee the argument would fail.”
  • “Concludes, from the fact that X occurred and that Y would ensure that X occurred, that Y must have occurred.”

In most cases, the answer simply states that somebody has mistaken a necessary condition for a sufficient condition. Until you become familiar with the underlying problem and the way the LSAT writers word these “mistaken reversal (TM)” answers, these can be baffling. After you recognize the problem and the pattern, they become quite simple.

Flaws: Assumption

When a “flaw” answer to an LSAT logical reasoning question contains words like “takes for granted” or “presumes, without justification,” you are dealing with an assumption of some kind. When you assume something that is necessary to the argument, you are definitely engaging in flawed reasoning. (As the old saying goes, “When you assume, you make an ass of u and me.”) Not every assumption is a necessary assumption, however, so the challenge is to discern whether this particular assumption is essential to this argument.

If an assumption is truly necessary, the argument self-destructs if you assume the logical opposite. Thus, for example, if I say, “Tuna is Marcia’s favorite lunch, so she is going to love my solid white albacore salad,” you have to assume that “albacore” is a kind of tuna. If you assume that albacore is not a type of tuna, the whole argument falls apart. You can always determine whether an assumption is truly necessary by seeing what happens when you assume its opposite.

This is why “extreme” statements are so seldom truly necessary assumptions. If I make an extreme assumption (for example, “solid white albacore is the only type of tuna”), then the logical opposite of that assumption generally won’t contradict the conclusion. Thus, if I assume that there other types of tuna besides albacore, my wife may still love her lunch.

That doesn’t mean that extreme answers are always wrong, however! You should check an extreme answer by assuming the logical opposite, and then see what effect that has on the argument. If an extreme answer is the right answer, assuming the opposite makes the argument fall apart. If it is the wrong answer, the opposite assumption has no real impact on the argument as a whole.

(It takes a little training to properly negate a logical statement. The logical opposite of “white” is not “black,” as you might suppose, but “not white.” Thus, pink, green, or tangerine are equally the opposite of white (in a logical sense). 7Sage.com has this post on how to find the logical opposite.)

Flaws: Overlooked Possibility

There’s something wrong with your thinking when you “overlook the possibility” or “fail to consider” something. That’s why these phrases show up so often in “flaw” questions in the logical reasoning section of the LSAT.  (There are an average of 7 “overlooked possibility” answers per test.) You’ll see the same sort of answers on “weaken the argument” questions, with one little difference. The right answer to a weaken question may say, “There is more than one type of tuna.” The right answer to a flaw question may say, “Fails to consider that there is more than one type of tuna.” It is the failure to consider this possibility that turn it into a case of “flawed reasoning.”

The most reliable way to work through any overlooked possibility answer is to use what I call “JY Ping’s Unless Test.” This can  be found in the 7Sage LSAT curriculum. I have been informed by my students that JY Ping, who is one of God’s gifts to aspiring law students everywhere, suggests that you sort out a “weaken” stimulus into its evidence and conclusion and then read it out as follows:

  • BECAUSE [evidence]
  • THEREFORE [conclusion]
  • UNLESS [answer]

Thus, we might see a question like this:

  • BECAUSE My wife loves tuna for lunch
  • THEREFORE She will love this solid white albacore tuna salad
  • UNLESS There is more than one type of tuna

(Note: there is more than one type of tuna and, no, Marcia doesn’t love solid white albacore!)

As you work through flaw questions with a “fails to consider” or “overlooks the possibility” answer, say the word “unless” and then read that answer off to yourself. If this doesn’t immediately and always get you the right answer, spend a little time on that question to see whether this technique will work for you. Leave a comment if it doesn’t help you on a particular question and I’ll see what I can do to make this clearer!

Flaws: Mistaken Most

“Most” is a common and dangerous word on the LSAT. I routinely tell students that “‘most’ is mostly wrong” because there are so many easy ways to write a wrong answer using “most.” It is no wonder, then, that one of the most common parallel flaw patterns is the “mistaken most.” Here are some examples:

Most mammals have four legs.
All dolphins are mammals.
THEREFORE most dolphins have four legs.

Most mammals have four legs.
Dolphins do not have four legs.
THEREFORE dolphins probably aren’t mammals.

Most Congressmen live near Washington, DC.
Most US citizens don’t live near Washington, DC.
THEREFORE, there must be more Congressmen than citizens near Washington, DC.

Flaws: Subjective/Objective Problem

Some flawed LSAT arguments infer a person’s intent from his or her actions (or vice versa).  If I were to accidentally knock a child down, I would not necessarily be guilty of child abuse.

This “subjective/objective” problem shows up periodically on the LSAT, but it is not otherwise common enough to be listed as a major fallacy. It only appears twice in 10 Actual Official LSAT Preptests, Volume VI (once as a correct answer and once as a wrong answer).

  • 72-2-5: Firepower movie (Vol VI, p. 16). 83% identified this as the correct answer to this “medium difficulty” question.
  • 74-4-18: Melatonin (Vol VI, p. 116). 7% chose this wrong answer to this “hardest difficulty” question.

Volume VI Flaws

The following work-in-progress is a hyperlinked list of the ANSWERS to flaw questions in “10 Actual Official LSAT Preptests Volume VI.” This document should immediately increase your accuracy on flaw questions by explaining what each answer means. If you carefully study the different flaws and the words the LSAT authors use to describe it, you should be able to get more right answers in less time in the LSAT logical reasoning section,

I recommend that this document be used as part of the 7Sage “blind review” method. Try to figure out each flaw question on your own, and then, without checking your  answer, look at that question in this document.  If you aren’t familiar with the labels I use  to describe the different flaws, just click the hyperlink to see what Wikipedia or other authors have said about this specific flaw. Then, after you are clear on what each answer actually means, choose your answer. If it is the same answer you originally chose, congratulations! If you changed your answer, congratulations again–you may have just learned something that will help you get into the law school of your choice!

72-2-5: Firepower movie (p. 17)

  1. Ad hominem
  2. Correlation does not imply causation
  3. Fallacy of composition
  4. Overlooked possibility
  5. Subjective/objective problem

72-2-14: Chocolate depression (p. 19)

  1. Reducing cause eliminates effect
  2. Unrepresentative sample
  3. Correlation does not imply causation
  4. Mistaken reversal
  5. Vague conclusion

72-2-16: Too many artworks (p. 20)

  1. Overlooked possibility
  2. Assumption
  3. Assumption
  4. Overlooked possibility
  5. Assumption

72-2-18: Blood samples (p. 20)

  1. Assumption
  2. Overlooked possibility
  3. Overlooked possibility
  4. Overlooked possibility
  5. Assumption

72-2-20: Wild apples (p. 21)

  1. Overlooked possibility
  2. Overlooked possibility
  3. Assumption
  4. Internal contradiction
  5. Circular reasoning

72-2-22: Flawed pattern (p. 22) is a mistaken reversal

72-3-7: Comics and health (p.26)

  1. Overlooked possibility
  2. Overlooked possibility
  3. Assumption
  4. Assumption
  5. Assumption

72-3-11: Hiking trail (p. 27)

  1. Argument from ignorance
  2. Fallacy of composition
  3. Circular reasoning
  4. Hasty generalization
  5. Ad hominem

72-3-14: Wildlife activists (p. 28)

  1. Mistaken negation
  2. Complete rejection of partial solution
  3. Overlooked possibility
  4. Ad hominem
  5. Rejection of one possible solution

72-3-22: Pathogenic microorganisms (p. 30)

  1. Overlooked possibility
  2. Overlooked possibility
  3. Overlooked possibility
  4. Overlooked possibility
  5. Overlooked possibility

72-3-25: Flawed pattern (p. 31) is a false dilemma

73-2-3: Movie rights to video games (p. 56)

  1. Hasty generalization
  2. Mistaken inference
  3. Circular reasoning
  4. Assumption
  5. Mistaken reversal

73-2-5: Primeval atom (p. 57)

  1. Appeal to authority
  2. Equivocation
  3. Correlation does not imply causation
  4. Evidence may support more than one hypothesis
  5. False dilemma

73-2-7: Flawed pattern (p. 58) is ad hominem

73-2-13: Crime rate (p. 59)

  1. Assumption
  2. Overlooked possibility
  3. Overlooked possibility
  4. Assumption
  5. Assumption

73-2-15: Advertising campaign (p. 60)

  1. Assumption
  2. Overlooked possibility
  3. Assumption
  4. Assumption
  5. Mistaken reversal

73-2-18: Planimetric art (p.61)

  1. Ad hominem
  2. Equivocation
  3. Mistaken reversal
  4. Internal contradiction
  5. Argument from ignorance

73-4-3: Sunscreen lotions (p. 73)

  1. Assumption
  2. Overlooked distinction
  3. Overlooked possibility
  4. Statistical error
  5. Overlooked possibility

73-4-10: Vacuum cleaner (p. 74)

  1. Overlooked possibility
  2. Assumption
  3. Assumption
  4. Overlooked possibility
  5. Overlooked possibility

73-4-18: Flawed pattern (p. 77) is the gambler’s fallacy

73-4-25: Roberta is irritable  (p. 79)

  1. Correlation does not imply causation
  2. Circular reasoning
  3. Hasty generalization
  4. Mistaken reversal
  5. Mistaken reversal

74-1-5: Children’s television (p. 89)

  1. Mistaken reversal
  2. Argument from ignorance
  3. Ad hominem
  4. Appeal to authority
  5. Internal contradiction

74-1-16: Pedagogical practice (p. 92)

  1. Concedes opponent’s assumption
  2. Assumption
  3. Overlooked possibility
  4. Equivocation
  5. Assumption

74-1-18: Sleep deprivation (p. 93)

  1. Alternate cause
  2. Alternate cause
  3. Mistaken reversal
  4. Assumption
  5. Overlooked possibility

74-1-25: Flawed pattern (p. 95) is mistaken reversal

74-4-8: Kodiak bear (p. 114)

  1. Hasty generalization
  2. Overlooked possibility
  3. Equivocation
  4. False dilemma / Assumption
  5. Appeal to authority

74-4-15: Interest rates (p. 115)

  1. Relies on experts
  2. Confuses terms
  3. Assumption
  4. Mistaken negation
  5. Unwarranted inference

74-4-18: Melatonin (p. 116)

  1. Subjective/objective problem
  2. Bias
  3. Equivocation
  4. Reverse cause
  5. Unrepresentative sample

74-4-20: Global recessions (p. 117)

  1. Circular reasoning
  2. Fails to establish claim
  3. Circular reasoning
  4. Overlooked possibility
  5. Possibility v. Certainty

74-4-22: Fish with teeth (p. 117)

  1. Correlation does not imply causation
  2. Argument from ignorance
  3. Mistaken negation
  4. Possibility v. Certainty
  5. Appeal to authority

74-4-25: Flawed pattern (p. 119) is a mistaken most

75-1-7: Sherwood opposes higher taxes (p. 130)

  1. Unrepresentative sample
  2. Overlooked possibility
  3. Mistaken negation
  4. Ad hominem
  5. Fallacy of division

75-1-12: Duke of Acredia (p. 131)

  1. Overlooked possibility
  2. Contrapositive (not a flaw)
  3. Unreliable evidence
  4. Correlation does not imply causation
  5. Assumption

75-1-18: Police graft (p. 132)

  1. Hasty generalization
  2. Overlooked possibility
  3. Appeal to character
  4. Assumption
  5. Internal contradiction

75-1-22: Flawed pattern (p. 134) is mistaken most

75-3-7: Profit projections (p. 145)

  1. Assumption
  2. Overlooked distinction
  3. Overlooked possibility
  4. Hasty generalization
  5. Equivocation

75-3-10: Television host (p. 146)

  1. Argument from ignorance
  2. Circular reasoning
  3. Appeal to authority
  4. Confuses standards
  5. Questions conclusion merely because it was reached quickly

75-3-14: Flawed pattern (p. 147) is unique

75-3-16: Planned locomotion (p. 148)

  1. Mistaken reversal
  2. Assumption
  3. Assumption
  4. Assumption
  5. Assumption

74-3-18: Consumer advocate (p. 149)

  1. Mistaken reversal
  2. Overlooked possibility
  3. Unrepresentative sample
  4. Assumption
  5. Assumption

76-2-1: Reptile hormones (p. 176)

  1. Provides no explanation for other abnormalities
  2. Overlooked possibility (resolves the mistaken reversal in the stimulus)
  3. Overlooked possibility
  4. Overlooked possibility
  5. Unrepresentative sample

76-2-4: Chameleon behavior (p. 177)

  1. Hasty generalization
  2. Fails to explain
  3. Appeal to authority
  4. Fails to demonstrate
  5. Holds critics to a higher standard

76-2-16: Legislature survey (p. 180)

  1. Is/ought problem
  2. Circular reasoning
  3. Fallacy of composition
  4. Survey error
  5. Rough estimates yield precise conclusion

76-2-19: Union leaders (p. 181)

  1. Genetic fallacy
  2. Assumption
  3. Genetic fallacy
  4. Assumption
  5. Assumption

76-2-21: Flawed pattern (p. 182) is multiple causes

76-4-5: Traditional rituals (p. 193)

  1. Assumption
  2. Assumption
  3. Assumption
  4. Assumption
  5. Assumption

76-4-6: Flawed pattern (p. 193) is affirming a disjunct

76-4-13: Government statistics (p. 195)

  1. Equivocation
  2. Overlooked possibility
  3. Overlooked possibility
  4. Overlooked possibility
  5. Assumption

76-4-15: Nutritional supplements (p. 195)

  1. Equivocation
  2. Appeal to authority
  3. Appeal to emotion
  4. Ad hominem
  5. Assumption

77-2-5: Flawed pattern (p. 217) is unique.

77-2-14: Cancer and pollutants (p. 220)

  1. Overlooked possibility
  2. Overlooked possibility
  3. Assumption
  4. Overlooked possibility
  5. Overlooked possibility

77-2-18: Shakespeare snobs (p. 221)

  1. Assumption/Ad hominem
  2. Assumption
  3. Overlooked possibility
  4. Overlooked possibility
  5. Circular reasoning

77-2-22: More than one newspaper (p. 222)

  1. Confuses inabilities
  2. Overlooked possibility
  3. Is/ought problem
  4. Assumption
  5. Concerned only with important stories

77-4-6: Popular sports (p. 233)

  1. Correlation does not imply causation
  2. Hasty generalization
  3. Equivocation
  4. Circular reasoning
  5. Ad hominem

77-4-9: Joshi campaign (p. 234)

  1. Correlation does not imply causation
  2. Mistaken reversal
  3. Is/ought problem
  4. Reverse causation
  5. Circular reasoning

77-4-12: Movie critics (p.235)

  1. Argument from ignorance
  2. Overlooked possibility
  3. Unrepresentative sample
  4. Ad hominem
  5. Overlooked possibility

77-4-15: Flawed pattern (p. 239) is hasty generalization

78-1-7: Air traffic (p. 249)

  1. Hasty generalization
  2. Overlooked possibility
  3. Overlooked possibility
  4. Argument from ignorance
  5. Overlooked possibility

78-1-9: Prairie plants (p. 250)

  1. Reverse causation
  2. Fails to describe mechanism
  3. Assumption
  4. Unrepresentative sample
  5. Numbers v. Percents

78-1-21: Flawed pattern (p. 254) is “‘or’ does not equal ‘and’.” (This is an especially difficult question because the phrase “sand or organic material, or both” sounds so plausible. If you replace “organic material” with “pixie dust,” however, the flaw becomes apparent.)

78-1-22: Toxic chemicals (p. 254)

  1. Internal contradiction
  2. Overlooked possibility
  3. Argument from ignorance
  4. Reverse causation
  5. Overlooked possibility

78-3-1: Nonprofit  organization (p. 264)

  1. Unrepresentative sample
  2. Assumption
  3. Survey error
  4. Relies on majority opinion to determine minority opinion
  5. Assumption

78-3-5: Site drainage (p. 265)

  1. Overlooked possibility
  2. Overlooked possibility
  3. Overlooked possibility
  4. Overlooked possibility
  5. Overlooked possibility

78-3-15: Good manager (p. 267)

  1. Confuses qualities
  2. Confuses qualities
  3. Mistaken reversal
  4. Overlooked possibility
  5. Assumption

78-3-25: Flawed pattern (p. 271) is mistaken most.

79-1-2: Trusting neighbors (p. 288)

  1. Mistaken negation
  2. Is/ought problem
  3. Internal contradiction
  4. Circular reasoning
  5. Reverse causation

79-1-6: Body size (p. 289)

  1. Alternate causation
  2. Unrepresentative sample
  3. Alternate causation
  4. Fallacy of division
  5. Hasty generalization

79-1-13: Zoo animals (p. 291)

  1. Assumption
  2. Hasty generalization
  3. Straw man
  4. Mistaken reversal
  5. Rejects a claim because its proponent holds an inconsistent view

79-1-15: Success and luck (p. 291)

  1. Mistaken reversal
  2. Appeal to authority
  3. Circular reasoning
  4. Reverse causation
  5. Ad hominem

79-1-26: Flawed pattern (p. 295) is “some dogs are pets but no cats are dogs so no cats are pets.”

79-4-9: Fitness experts (p. 314)

  1. Correlation does not imply causation
  2. Assumption
  3. Infers that a factor that is a contributor is the only contributor
  4. Hasty generalization
  5. Fallacy of division

79-4-16: Flawed pattern (p. 316) is mistaken reversal

79-4-18: High school graduates (p. 316)

  1. Fails to establish
  2. Overlooked possibility
  3. Assumption
  4. Assumption
  5. Assumption

80-1-2: Hair dryers (p. 328)

  1. Numbers v. Percents
  2. Does not provide specific information
  3. Fails to discuss sales figures
  4. Overlooked possibility
  5. Provides no independent evidence

80-1-13: Purpose of laws (p. 331)

  1. Mistaken negation
  2. Correlation does not imply causation
  3. Equivocation
  4. Is/ought problem
  5. Fallacy of division

80-1-16: Commercial flights (p.332)

  1. Assumption
  2. Overlooked possibility
  3. Ad hominem
  4. Assumption
  5. Argument from ignorance

80-1-24: Flawed pattern (p. 335) is mistaken most

80-4-1: Community cleanup (p. 352)

  1. Hasty generalization
  2. Assumption
  3. Mistaken reversal
  4. Overlooked possibility
  5. No true Scotsman

80-4-11: University food vendor (p. 355)

  1. Overlooked possibility
  2. Unrepresentative sample
  3. Overlooked possibility
  4. Overlooked possibility
  5. Argues that a popular position ought to be adopted

80-4-16: Software company logo (p. 356)

  1. Correlation does not imply causation
  2. Mistaken negation
  3. Fallacy of division
  4. Circular reasoning
  5. Hasty generalization

80-4-23: Flawed pattern (p. 358) is roll the dice

80-4-26: Macedonian tombs (p. 359)

  1. Assumption
  2. Assumption
  3. Does not show
  4. Fails to evaluate
  5. Assumption

81-2-8: Employee bonuses (p. 377)

  1. Overlooked possibility
  2. Overlooked possibility
  3. Fails to justify
  4. Fallacy of division
  5. Assumption

81-2-20: Voting records (p. 381)

  1. Faulty comparison
  2. Fails to take into account
  3. Provides evidence but not explanation
  4. Reverse causation
  5. Overlooked possibility

81-2-24: Flawed pattern (p. 383) is argument from ignorance

81-2-25: Technological innovations (p. 383)

  1. Circular reasoning
  2. Argument from ignorance
  3. Stronger evidence than conclusion requires
  4. Mistaken reversal
  5. Hasty generalization

81-3-7: Economic productivity (p. 386)

  1. Assumption
  2. Assumption
  3. Unfairly criticizes politicians in general
  4. Assumption
  5. Fails to address

81-3-9: Brain area (p. 386)

  1. Assumption
  2. Overlooked possibility
  3. Hasty generalization
  4. Overlooked possibility
  5. Assumption

81-3-13: Legislator investment (p. 388)

  1. Treats a character trait as evidence of a viewpoint
  2. Fails to address the argument
  3. Assumption
  4. Assumption
  5. Overlooked possibility

81-3-15: Car manufacturers (p. 388)

  1. Hasty generalization
  2. Assumption
  3. Overlooked possibility
  4. Assumption
  5. Equivocation

81-3-23: Negotiated legislation (p. 391)

  1. Circular reasoning
  2. Mistaken negation
  3. Equivocation
  4. Assumption
  5. Bases conclusion on a different principle

Grow Your Brain

I believe that most students can improve on the LSAT, for two reasons. First, I’ve seen it done. Second, I suspect that the brain actually grows when it is repeatedly exercised. Recent research supports this idea.

Researchers at Berkeley studied a group of students who are preparing for the LSAT. They imaged their brains before and after a three-month BluePrint course, and compared those results to a control group of similar students who weren’t preparing for the LSAT. They found that the LSAT students had measurably more “white matter” (the axons that connect the “gray matter” of the neurons). Here’s a popular write-up and here’s the published research.

I work on the assumption that repeated stimulation of neurons changes them in some way. The neural network experts assure me that the receiving end of a neuron (the “dendrite”) changes with use, and the Berkeley research shows that there is some change to the sending end (the “axon”) as well. I assume that thinking hard, long, and often about any topic will increase the number of possible connections between nerve cells, resulting in long-term change to the brain itself.

To boil this down to a bumper sticker, you are what you think. Think a lot about any given topic, and you’ll wind up thinking more about it.  That’s bad news if the topic is lust, rage, greed, or fear. It’s good news if you want to go to law school and you’re thinking about logical reasoning!

 

Time Tactics: Simple Global Must Be True Questions

Before I decided I needed time tactics, I often spent two minutes on a logic game question that I should have gotten right in ten or fifteen seconds. The question would be something simple: “Which of the following must be true?” Time after time, I would slog my way through answer choice A, B, C, and D, proving that each one might be false. Then I would reach answer choice E and realize that it must be true–I already had it penciled in on my diagram. The geniuses who write the LSAT know all about people like me, and they routinely set us up for failure. But once you study time tactics, you can beat them at their own game.

A question like “which of the following must be true” is a global “must be true” question. In subsequent chapters, we will talk about “local” questions (where the question begins with an “if” that established a new condition for just that one question) and “must be false” questions. As we explore the different variations of “must be” questions, we will discover the optimal path through all such problems. For now, our “must be method” is very simple:

Must Be Method:
1) Could be easy!

Let’s try this out on the following simple sequencing game. Here are the scenario and rules:

Six law students–Allison, Briyant, Clarence, Daniel, Elisheva, and Faith–decide to chase Pokémon instead of studying. Each student catches exactly one Pokémon at a time. The order in which they catch them is determined by the following rules:

Elisheva catches hers before Daniel,
Allison gets hers first or last.
Neither Elisheva nor Faith catches the first one.
Clarence catches his before Allison or Briyant but not both.

Here is my sketch for this game. The blue items on the diagram are spelled out in the initial rules; the orange items are deductions I have made.

Note: several of our time tactics depend on being able to quickly and accurately check through all the rules, so I list all of the rules in order. If a rule can be completely expressed directly on the diagram, I note that to the left of the rule number; otherwise I write in the rule to the right of the rule number.

Turn on your stopwatch app and see how long it takes you to answer the following question.

Which of the following must be true?

A) At least two students catch a Pokémon before Allison.
B) At least two students catch a Pokémon before Briyant.
C) At least two students catch a Pokémon before Clarence.
D) At least two students catch a Pokémon before Daniel.
E) At least two students catch a Pokémon before Elisheva.

How long did that take? Think about the way you went about answering the question.

Now let’s apply our “could be easy” tactic to this same question. Every single answer mentions “at least two students,” which ought to focus our attention somewhere on the diagram. If at least two students must go before somebody, that somebody can’t go first or second. A quick look at the diagram shows that Daniel is the only student who can’t go second–and he can’t go first, either. Answer choice D is about Daniel–and we’re done!

Your elapsed time for this question, which includes reading the question, looking at the answers, checking the second spot on the diagram, and finding answer choice D should be about fifteen to twenty seconds.

Note–this kind of speed depends on having deduced that Daniel couldn’t catch the second Pokémon when you first set up the game. If you don’t routinely see such deductions when you first go through the rules, you need more work on logic game basics. Don’t worry about that now, however–throughout this book, you’ll have my diagrams in front of you as you tackle each question.

Let’s sum up what we’ve learned about the “could be easy” rule. A “must be true” question could be so easy that you can just look at your diagram and find the answer in a matter of seconds. This is especially likely to be true if you made some good deductions on your setup. When you see a global “must be true” question, quickly skim through all five answers to find out whether you have already figured out the answer. If you have, grab that answer and go–you don’t need to look any further!

Time Tactics: Orientation Questions

The first question in most logic games is very predictable–it asks which of the following five answers are acceptable outcomes.  The Law School Admission Council refers to these as “orientation questions,” since they are intended to orient you to the setup conditions. In The Official LSAT Superprep II, the LSAC tells you exactly how to answer such questions:

For such questions, probably the most efficient approach is to take each condition in turn and check to see whether any of the answer choices violates it. As soon as you find an answer choice that violates a condition, you should eliminate that answer choice from future consideration–perhaps by crossing it out in your test booklet. When you have run through all of the setup conditions in this fashion, one answer choice will be left that you haven’t crossed out: that is the correct answer.

This paragraph is the gold standard for “how to solve a logic game problem.” It is short, accurate, and authoritative. It not only tells you how to get the problem right every single time, it tells you how to get it right as efficiently as possible. What The Official LSAT Superprep II doesn’t do is explain why this is the fastest and best way to answer such questions, nor does it explain why other methods are slower and less reliable.

There are three ways to solve an orientation question. The first (which is far too common) is to have no strategy. The second is to tackle the question rule by rule, as the LSAC suggests. The third is to start with answer choice A, go through the rules one by one, eliminate it if it breaks a rule, and move on to answer choice B. This “answer by answer” approach will usually produce the right answer–but it is significantly slower and less reliable than the “rule by rule” approach. Let me explain why.

The “rule by rule” approach is optimal because it minimizes time-consuming steps and eliminates the possibility of “false positives.” By “false positive,” I mean an answer that appears to obey all the rules but really doesn’t. The people who write logic games know how most people try to solve them, and they can and will use that against you. Thus, if answer choice C appears to follow every rule, it can still be wrong–some other rule may be buried in the initial paragraph that spells out the scenario. You can’t really be sure that C is right until you know that every other answer is wrong,

Here are the steps for a “rule by rule” solution:

  1. Look at the rule.
  2. Figure out what you’re looking for in a wrong answer (i.e., “if A comes before B, that breaks this rule”).
  3. Skim through each answer choice, looking for that pattern.
  4. Cross off any answer(s) that break the rule.
  5. Go back to step 1 and repeat until only one answer is left.

Compare that to the “answer by answer” approach:

  1. Look at the answer.
  2. Go up to the first rule.
  3. Figure out what you’re looking for in a wrong answer (i.e., “if A comes before B, that breaks this rule”).
  4. Go back to your answer, looking for that pattern.
  5. Cross off the answer if it breaks the rule and jump ahead to  step 18.
  6. Otherwise, go up to the second rule.
  7. Figure out what you’re looking for in a wrong answer (i.e., “if A comes before B, that breaks this rule”).
  8. Go back to your answer, looking for that pattern.
  9. Cross off the answer if it breaks the rule and jump ahead to step 18.
  10. Otherwise, go up to the third rule.
  11. Figure out what you’re looking for in a wrong answer (i.e., “if A comes before B, that breaks this rule”).
  12. Go back to your answer, looking for that pattern.
  13. Cross off the answer if it breaks the rule and jump ahead to step 18.
  14. Otherwise, go up to the fourth rule.
  15. Figure out what you’re looking for in a wrong answer (i.e., “if A comes before B, that breaks this rule”).
  16. Go back to your answer, looking for that pattern.
  17. Cross off the answer if it breaks the rule.obeys
  18. This is the step where you get in trouble. Is this the final answer choice? Is it the only one that isn’t crossed off? If you haven’t reached answer choice E yet, you could be making a big mistake right here. So if you aren’t at E yet, move on to the next answer and go back to step 1.

That’s the theory. Let’s put it into practice. Here’s a simple orientation question for a logic game:

Allison, Bradley, Clarence, Daniel, Elisheva, and Faith are so tired of prepping for the LSAT that they have all decided to play Pokémon Go. Between them, they manage to catch and hatch Pheremosa, Quagsire, Relisprout, Solgaleo, Togetic, and Uxie. Each Pokémon is caught one at a time, but not every law student necessarily catches a Pokémon. The order in which the students catch the Pokémon obeys the following rules:

Bradley refuses to catch a Pokémon until Allison gets one.
None of the girls try to catch more than one Pokémon.
Uxie is caught first or last.
Pheremosa is  caught after Relisprout.

Question 1: Which of the following is an acceptable list of the order of students and the Pokémon they catch?

A) Daniel catches Uxie, Allison catches Relisprout, Bradley catches Pheremosa, Faith catches Quagsire, Bradley catches Sogaleo, Clarence catches Togatic.

B) Allison catches Relisprout, Bradley catches Uxie, Daniel catches Pheremosa, Faith catches Quagsire, Elisheva catches Sogaleo, Bradley catches Togatic.

C) Clarence catches Uxie, Daniel catches Sogaleo, Faith catches Relisprout, Allison catches Pheremosa, Bradley catches Quagsire, Faith catches Togatic.

D) Allison catches Relisprout, Faith catches Quagsire, Bradley catches Pheremosa, Daniel catches Sogaleo, Bradley catches Togatic, Daniel catches Uxie.

E) Bradley catches Uxie, Allison catches Relisprout, Clarence catches Pheremosa, Faith catches Togetic, Elisheva catches Quagsire, Daniel catches Sogaleo.

I solved this problem “answer by answer.” It took me 1:16, and I sort of cheated because I stopped when I got the answer that obeyed all the rules. (If this had been a tricky question with a rule buried in the scenario, I would have gotten it wrong.) I did the same problem “rule by rule” and it took my 0:36. That’s just under half as long and the answer was more trustworthy–I eliminated four wrong answers and the only answer left had to be right.

Try this yourself. If you don’t see a dramatic difference between the “answer by answer” and the “rule by rule” approach, leave a comment below. If you do find that the “rule by rule” approach is significantly faster (and more reliable), make sure you use it from now on. You’re on your way to learning time tactics!