Inference Questions: Wrong Answer Types

There are several different kinds of “inference questions” on the LSAT. Some are perfect examples of pure conditional reasoning, such as the “must be true” and “must be false” questions in logical reasoning and logic games. Others are “softer” inferences, such as the “most strongly supported” –questions in logical reasoning and the “author is most likely to agree” type statements in reading comprehension. There are important similarities between these different questions, and even more important similarities between the wrong answers to these questions.

In this post, we will look reading comprehension inference questions. These are functionally identical to the “most strongly supported” logical reasoning questions, with the added challenge of searching sixty lines of reading comp to find the answer instead of the typical six-to-twelve line logical reasoning stimulus. All that text means that a clever and imaginative student can conjure up some reason a wrong answer might be right. (I’ve seen it done… and I’ve even done it myself!) That is a problem for LSAT takers and for the people who write it. The LSAT authors always include the word “most” in phrases like “which of the following is most strongly supported” to respond to students who call up to complain that some other answer is arguably correct, but they don’t want to have that conversation. They want each wrong answer to be provably wrong–and there are only so many ways to do that. Learn that handful of “wrong answer techniques,” and you will get faster and better at inference questions.

Quantities and Comparisons

The easiest wrong answer involves a “quantity” claim that is not supported by the text. The easiest way to generate such an answer is to take a sentence that is clearly stated in the text and then add one “quantity word” that isn’t in the text. Thus, if the passage says “ultraviolet light causes skin cancer” don’t be surprised if you see a wrong answer that claims that “ultraviolet light is the primary cause of skin cancer.”

“Comparison words” are common in wrong answers, for several reasons. Consider an answer like “The diversity of plant species was greater in ancient forests than in modern forest.” For that to be the right answer, we will need information about the plant diversity in ancient forests, the plant diversity in modern forests, and some common unit of measurement that allows us to compare them. It isn’t enough to say “there were lots of plant species in ancient forests” and “modern forests have many different species.” That doesn’t tell us which has more. Comparison answers can be right, but only if there is clear and specific information to support it–and that is the exception, not the rule.

Sounds good but not supported

An answer is provably wrong if it includes an element that never appears in the passage. The LSAT authors must tempt test-takers to choose such an answer, so they often write an answer choice that appeals to the readers common sense or preconceptions. If your initial response to answer is “that is probably true,” be careful! The question before you is not “what is true” but “what is supported by the text.”

Using Aristotle’s Tools

Aristotle worked out almost all of the rules of categorical reasoning more than 2300 years ago, and logic students for the last two millenia have been learning how to apply them. Since the Law School Aptitude Test is primarily a test of logical reasoning, these rules may be able to help law students, too. This post is for students who know the basics of categorical reasoning and want to learn how to use Aristotle’s tools to do better on the LSAT.

There are four types  of categorical statements:

Universal Affirmative (“A”): All subjects are predicates
Universal Negative (“E”): No subjects are predicates
Particular Affirmative (“I”): Some subjects are predicates
Particular Negative (“O”): Some subjects are not predicates

These four types of statements “distribute” their terms in different ways. A term is “distributed” if the categorical statement tells you something about every member of that category. Here is how the terms are distributed in the four types of statements:

A (“All subjects are predicates”): subject is distributed, predicate is not
E (“No subjects are predicates”): subject is distributed, predicate is distributed
I (“Some subjects are predicates”): subject is not distributed, predicate is not distributed
O (“Some subjects are not predicates”): subject is not distributed, predicate is distributed. (This last category is much less intuitive than the other three! If you say, “Some presidents are not Caucasian,” then you may assert that every Caucasian is not that president–i.e., not Barack Obama.)

There is a standard form for categorical syllogisms:

Major premise: Major term and Middle term
Minor premise: Minor term and Middle term
Conclusion: Minor term (subject) and Major term (predicate)

There are several rules for categorical statements:

  1. There must be exactly three terms, each of which is used in the same sense.
  2. The middle term must be distributed in at least one premise.
  3. If a term is distributed in the conclusion, it must be distributed in at least one premise.
  4. No argument may have two negative premises.
  5. If an argument has a negative premise, it must have a negative conclusion.
  6. If an argument has two universal premises, it cannot have a particular conclusion.

With these tools in hand, let us see how they work on some “sufficient assumption” questions. (All of the  following examples are from the June 2007 LSAT, which the LSAC has placed in the public domain.)

Section 2, Question 6

An undergraduate degree is necessary for appointment
to the executive board. Further, no one with a felony
conviction can be appointed to the board. Thus,
Murray, an accountant with both a bachelor’s and a
master’s degree, cannot be accepted for the position of
Executive Administrator, since he has a felony

The conclusion of this argument is “Murray… cannot be accepted for the position of Executive Administrator.” If we treat “Murray” as the “category of all Murrays” we can rewrite this as “No Murray is an Executive Administrator.” “Murray” is the subject of this conclusion (which makes “Murray” the “minor term”) and “Executive Administrator” is the predicate (which makes that the “major term”). We can sketch out the “standard form” categorical syllogism as follows:

Major premise: Executive Administrator AND Middle Term
Minor premise: Murray and Middle Term
Conclusion: No Murray is an Executive Administrator

Applying our rules to what we have so far, one of our premises must be positive and the other must be negative. The conclusion is an “E” type statement (“No S is P”), which means that both the major and minor terms are distributed in the conclusion. That means they must also be distributed in at least one premise. The middle term must also be distributed. Thus, every term must be distributed.

The only way to get that many distributed terms with one positive premise is to have one “A” type premise (“All S is P”) and one “E” type premise (“No S” is “P”).  That means we must either have an “All  Murray is (Middle term)” or “No Murray is (Middle term).”

Looking at the  stimulus, we see an “A” type statement about Murray. “Murray has a felony conviction.” Let’s plug that new information into our standard form, and make the other premise an “E” type statement that uses “felony conviction” as the middle term:

Major premise: No Executive Administrator has a felony conviction
Minor premise: (All) Murray has a felony conviction
Conclusion: No Murray is an Executive Administrator

Do we have an answer that says, “No Executive Administrator has a felony conviction”? Unfortunately, no. That doesn’t mean we’re wrong in our analysis–just that there’s more information in the stimulus.

The stimulus tells us that “no one with a felony conviction can be appointed to the executive board.” That gets us very close to the answer we need! Answer Choice B says, “Only candidates eligible for appointment to the executive board can be accepted for the position of Executive Administrator. When we combine that with “no one with a felony conviction can be appointed to the executive board,” we get “No Executive Administrator has a felony conviction.” Answer Choice B is the correct answer.

Section 2, Question 15

A new government policy has been developed to avoid
many serious cases of influenza. This goal will be
accomplished by the annual vaccination of high-risk
individuals: everyone 65 and older as well as anyone
with a chronic disease that might cause them to
experience complications from the influenza virus.
Each year’s vaccination will protect only against the
strain of the influenza virus deemed most likely to be
prevalent that year, so every year it will be necessary
for all high-risk individuals to receive a vaccine for a
different strain of the virus.

The conclusion here  is “every year it will be necessary for all high-risk individuals to receive a vaccine for a different strain of the virus.” That is an A-type statement, “All years’ vaccines are vaccines for a different strain of the virus,” which we can simplify to “All Years’ Vaccines are Different Vaccines.” Putting that in standard form:

Major premise: Different Vaccines AND Middle term
Minor premise: Year’s Vaccines AND Middle term
Conclusion: All Year’s Vaccines are Different Vaccines

The  conclusion is affirmative, which means we cannot have any negative premises. The minor term is distributed, which means we must have a premise which distributes that term. That can only be “All Years’ Vaccines are (Middle term).” The middle term is not distributed in that statement, but it must be distributed somewhere, and there is only one way to do that using an affirmative statement: “All (Middle term) Different Vaccines.” We can write out  our  standard form as:

Major premise: All Middle Term are Different Vaccines
Minor premise: All Year’s Vaccines are Middle Term
Conclusion: All Year’s Vaccines are Different Vaccines

Looking at our stimulus, we see that “each year’s vaccination will protect only against the strain of the influenza virus deemed most likely to be prevalent that year.” Let’s plug that in as our middle term.

Major premise: All vaccinations against the strain most likely to be prevalent are Different Vaccines
Minor premise: All Year’s Vaccines are vaccinations against the strain most likely to be prevalent
Conclusion: All Year’s Vaccines are Different Vaccines

Looking through the answers for “all vaccinations against the strain most likely to be prevalent are Different Vaccines,” we see “Each year the strain of influenza virus deemed most likely to be prevalent will be one that had not previously been deemed most likely to be prevalent.” That is the answer!

Section 2, Question 23

Philosopher: An action is morally right if it would be
reasonably expected to increase the aggregate
well-being of the people affected by it. An action
is morally wrong if and only if it would be
reasonably expected to reduce the aggregate wellbeing
of the people affected by it. Thus, actions
that would be reasonably expected to leave
unchanged the aggregate well-being of the people
affected by them are also right.

The conclusion is “actions that would be reasonably expected to leave unchanged the aggregate well-being of the people affected by then are (also) right,” which can be simplified as “All Actions that don’t affect aggregate well-being are Right actions.”

Major premise: Right actions and Middle term
Minor premise: Actions that don’t affect aggregate well-being and Middle term
Conclusion: All Actions that don’t affect aggregate well-being are Right actions

The conclusion is affirmative, and the minor term is distributed. There is only way to write an affirmative statement that distributes a term: “all actions that don’t affect aggregate well-being are Middle term.” That leaves the middle term undistributed, which means it must be distributed in the major term, which can only be  written one way: “All Middle term are right actions.” We can write out the standard form this way:

Major premise: All Middle term are right actions.
Minor premise: All actions that don’t affect aggregate well-being are Middle term.
Conclusion: All Actions that don’t affect aggregate well-being are Right actions

We have an affirmative conclusion, so we must have two affirmative premises. One statement in the stimulus says, “An action is morally wrong if and only if it would be reasonably expected to reduce the aggregate well-being of the people affected by it.” That is a double negative, of sorts–all actions that are NOT right actions are NOT actions that don’t affect aggregate well-being, and vice versa.

Aristotle’s rules aren’t getting us very far here. Let’s peek at some answer choices and see if any of them might line up with either our major premise or our minor premise. Answer choice C is the only one that fits the pattern at all. Let’s plug it in to our standard form:

Major premise: All actions that are not morally wrong are right actions.
Minor premise: All actions that don’t affect aggregate well-being are actions that are not morally wrong.
Conclusion: All Actions that don’t affect aggregate well-being are Right actions

Sure enough, that matches–the “if and only if” statement in the stimulus is logically equivalent to “all actions that don’t affect aggregate well-being are actions that are not morally wrong.”

Section 3, Question 5

Atrens: An early entomologist observed ants carrying
particles to neighboring ant colonies and inferred
that the ants were bringing food to their
neighbors. Further research, however, revealed
that the ants were emptying their own colony’s
dumping site. Thus, the early entomologist was

The conclusion here is “the early entomologist was wrong,” but that needs to be unpacked a bit. The entomologist concluded that “ants were bringing food,” so the opposite of that is “ants were not bringing food.” We can make that a categorical statement by saying, “No particles that ants were carrying were food particles.” Putting that in standard form, we have:

Major premise: food particles and Middle Term
Minor premise: particles that ants were carrying and Middle Term
Conclusion: No  particles that ants were carrying were food particles

The conclusion is negative and distributes both terms. Since the middle term must also be distributed and we must have one and only one negative premise, we must distribute every term with one affirmative premise and one negative premise. The only way to do that is to have one A-type statement and one E-type statement.

There aren’t a lot of choices for a middle term–the only additional information in the stimulus is about a dumping site, and that information is affirmative and relates to the particles the ants were carrying. We can pencil that in as our middle term:

Major premise: no food particles are particles from the dumping site
Minor premise: all particles that ants were carrying were from the dumping site
Conclusion: No particles that ants were carrying were food particles

Answer choice C is a match for our major premise. QED!

Section 3, Question 24

Sociologist: Romantics who claim that people are not
born evil but may be made evil by the imperfect
institutions that they form cannot be right, for
they misunderstand the causal relationship
between people and their institutions. After all,
institutions are merely collections of people.

The sociologist concludes that romantics can’t be right when they claim that people are not born evil but may be made evil by the imperfect institutions that they  form. The logical opposite of “people may be made evil by institutions” would be “no people are made evil by institutions.” This can be put in standard form:

Major premise: beings made evil by institutions and middle term
Minor premise: people and middle term
Conclusion: No people are beings made evil by institutions

The passive “things made evil by institutions” is questionable. We don’t have to write our conclusion in the passive voice. We could say, instead, that “no institutions are things that make people evil,” in which case our standard form would be:

Major premise: things that make people evil and middle term
Minor premise: institutions and middle term
Conclusion: No institutions are things that make people evil

As we have seen twice before, the conclusion is a universal negative, which means that we must distribute the major term, minor term, and middle term using one affirmative premise and one negative premise. This requires one A-type statement and one E-type statement, with the middle term undistributed in the A-type. If our first formulation is correct, one statement must read either “All people are middle term” or “All beings made evil by institutions are middle term.” If our  second formulation is correct, one statement must read either “All institutions are middle term” or “All things that make people evil are middle term.”

The stimulus states that “institutions are merely collections of people.” If we zero in on that as our middle term, we get:

Major premise: No collections of people are things that make people evil
Minor premise: All institutions are collections of people
Conclusion: No institutions are things that make people evil

Answer choice E is broad enough to include our major premise. That answer says, “The whole does not determine the properties of the things that comprise it.” That is certainly consistent with “No collections of people are things that make people evil,” and none of the other answers are anywhere close. That makes answer choice E our best bet.


If you can do categorical syllogisms in your sleep, using Aristotle’s rules would appear to provide a fairly reliable way to analyze sufficient assumption questions. That doesn’t mean that this is faster or better than other techniques!

Playing with a Full Deck

Countless successful students prove that people can see significant and sustained improvement on the LSAT over time. That’s great for them, but how can you get such results? Here is how I use index cards and the “blind review” process to help my students get the score they want.

There are lots of LSAT prep materials (PowerScore, Kaplan, Princeton Review, etc.). which range from “brief but useless” to “overlong and overwhelming.” You can buy a 900 page book that is “guaranteed” to raise your score, but the book won’t actually help you until something in that book enables you to eliminate a wrong answer or choose a right answer. If you’re lucky, those 900 pages might contain thirty concrete and specific insights or techniques that consistently affect your score.

I never require my students to buy any specific prep materials. I want them to make the most of whatever they start with, whether they come to me with the LSAC “SuperPrep” or the entire PowerScore LSAT Bible Trilogy. Instead, I help them figure out generally-applicable techniques that enable them to eliminate a particular wrong answer or identify a particular right answer, and write it out on my tutoring whiteboard in a format that would fit on an index card. At the end of each session, I expect them to save those whiteboards and copy out any new cards and add them to their personal card deck.

Once you have some cards in your personal deck, I will ask you to do one logical reasoning section under time pressure. For students who are already scoring at or above the national average (152), that means under 35 minutes. I don’t put a specific time limit on students who are still scoring under 152, but I do have them time each individual question with a stopwatch.

Once you complete that logical reasoning section under time pressure, don’t score it! You have completed the “testing” phase of the process, but you haven’t even started the “learning” phase. The next step is to “blind review” each question, using your personal card deck. Let’s walk through that process, using Section 2 of the  June 2007 LSAT (which is the only test that the LSAC makes generally available).

Question 1: Which one of the following most accurately expresses
the main conclusion of the economist’s argument?

Process: Do I have an index card for this? No, I don’t, because I usually get main point questions right. Looking at my test paper, I see that I originally underlined the phrase “not all efforts to increase productivity are beneficial” because it looked like the conclusion to me. I know that the conclusion is the phrase that everything else in the paragraph supports, and that’s true here. The answer I chose was B, which says,”Some measures to increase productivity fail to be beneficial.” I’m pretty sure that “Not all are” is logically identical to “Some are not,” so I’ll stick with my original answer. Since I double-checked my reasoning, I’m going to take my ball-point pen and draw a blue circle around the black pencil circle I started with. 

Question 2: Which one of the following uses flawed reasoning that
most closely resembles the flawed reasoning used in
the argument above?

Process: Parallel flaw–let’s see, I do have an index card for this one.

Parallel flaw: read the stimulus and see if you can spot the flaw.
If you can see it now, you can do it now.
If you can’t see the flaw, this will take longer than any other question and you’re still likely to get it wrong. Save it for last!
If you still haven’t seen the flaw, read the answers CAREFULLY. One of them has the hint you need.

Well, that’s good–because I couldn’t see the flaw with the clock ticking and I still can’t see it. Let’s look at the answers for hints. Nothing in A… B is interesting. If I mix something extremely toxic (like arsenic) with something non-toxic (like water), I’ll bet it’s still extremely toxic, not “moderately toxic.” That’s sort of like the stimulus–breeding a dog that barks a lot with a dog that doesn’t bark won’t necessarily give you a moderate barker. Let’s circle B with the blue pen. Since this card seems to have actually helped me here, let’s put a little tick mark in the top right corner of the card. 

Question 3: Which one of the following most logically completes
the argument?

Process: This looks like some kind of inference. I have a card for that.

1. Pick an answer.
2. Could the opposite of that answer ever happen?
3. Reread the stimulus–if the answer you picked CAN’T BE FALSE, you’re right!
4. Avoid answers that COULD BE TRUE, answers which reference something you have no information about, and answers which are EXPLANATIONS of the stimulus rather than DEDUCTIONS from it.

I picked answer A, “people at a century’s end reminisce about their own lives.” Could that ever be false? Maybe. I mean, some people may look back on their own lives but others wouldn’t. A might be wrong. Let me look at the others. B looks wrong–no information about fearing. C talks about looking forward to the next century. That COULD be true, but it doesn’t have to be true. D talks about the history of the century just ending. Could that be false? People don’t care about the century just ending, but the stimulus says that people behave toward the century much as a person behaves towards his or her own life. If we look back at our lives at the end of a century, I guess people at the end of a century must look back on the century. OK, let’s circle D in blue, and add a tick mark to the card. (Hmmm– that’s the fifth tick mark on this card. I guess I should be thinking about this while the clock is running–I want to  get this question right the first time, not just on blind review!)

Question 5: The reasoning in the consumer’s argument is most
vulnerable to criticism on the grounds that the

Process: Flaw! OK, there’s a card for every different answer to a flaw question. Let’s look at these answers. A talks about  bias. I have a card on this.

Flaw: Bias.
This is a specific form of the more general ad hominem fallacy, which attacks the person rather than the argument.
Bias may show that a witness is unreliable, but it does not prove that the witness is lying.
Any conclusion that says the opposite of what the biased witness says is flawed.

Let’s see–answer choice A starts with the phrase, “treats evidence that there is an apparent bias.” Yes, the stimulus does do that. It goes on “as evidence that the Connorly Report’s claims are false.  Yes, it does that, too. Looks like a perfect example of an ad hominem fallacy, which is what I though the first time. Keep the pencil circle around A–I’m so sure of this one that I’m not going to put a blue circle around it.

Question 6: The argument’s conclusion follows logically if which
one of the following is assumed?

Process: I hate these! OK, I know it’s an assumption question of some kind, but what kind? I have a card here somewhere…

C->A                                                   A->C
Does the question include the word “if”? Probably “sufficient.”
Does the question include words like “rely,” “depends”? Necessary.

OK, it does say “if” in the question. “If I assume, the conclusion follows.” Looks like it’s a sufficient assumption. (Add a tick mark to this card.) Now, I know I have another card about that.

1. Find the conclusion. Look for a new term. It MUST BE in the correct answer.
2. Find any term that appears both in the conclusion and a premise. It should not be in the correct answer.
3. There should not be any brand new term in the correct answer–only something that has already appeared in at least one premise.

Right. So the conclusion here is “Murray cannot be accepted for the position of Executive Administrator. Good–Executive Administrator is a new term. Knock off all the answers that don’t include that term. Oh–that’s answer A, which is what I picked! Well, put a tick mark on this card–if I had remembered this I wouldn’t have chosen that. Moving on to step 2; “Murray” appears in the conclusion and the premises, so I guess I can knock out D and E. Rule 3 doesn’t help me choose between B and C, so I guess I’ve gone as far as the “Mechanistic Approach (TM)” will get me. Good thing I have another card here…

With MBT, MSS, MBF: the ANSWER can’t be false.
With SA, PSA: the CONCLUSION can’t be false if  you pick the right answer.

So–the conclusion here is still, “Murray cannot be accepted for the position of Executive Administrator.” With answer choice B, Murray can’t be on the executive board (because he  has a felony conviction), which means he can’t be Executive Administrator. That looks pretty good. With C, there’s nothing to keep Murray from being Executive Administrator. OK, C is out and B is in. Put a blue circle around B and add a tick mark to this card. (Hmm. That’s the first time this card has actually helped me!)

Questions 7-25… repeat this process until you finish the section.

When you (finally!) finish blind reviewing that last question, you’re ready to score the section. I encourage all my students to set up a free account at (which may well be the single most fabulous LSAT resource on the Internet). 7Sage makes it easy to bubble in your blind review results–there’s a black bubble for your initial answer, and then, if you click on the question number, another line of blue bubbles pops up so that you can add your blind review result. When you save and score your answers, you’ll see your score for that section (and the test as a whole). In addition. 7Sage will sort the questions into “very low priority,” “low priority,” “high priority,” and “very high priority” questions.

The “very low priority” questions are those you got right the  first time. For self-study purposes, these “very low” questions are unimportant. Since you already got it right, there’s nothing new to learn!

The “low priority” questions, by contrast, are very important. You got this question wrong under time pressure, but got it right when you worked through it with your card deck. Go over these “low priority” questions and take another look at the card that helped you get it right. Ask yourself, “What could I do different next time so that I get this right while the clock is running?” You already know how to get this question right–now you need to get it right the first time.

The “high priority” questions are also very important. If you have a card for this situation, it isn’t helping you yet. If you don’t have a card that helps you here, it’s time to get one!  I ask my students to look over these high priority questions and flag the question on 7Sage if they can’t figure it out on their own. At our next tutoring session, we’ll use those flagged questions to figure out which generally-applicable insight or technique would help you get it right.

Over time, we will build up an index card deck that enables you to get a blind review score that is consistently ten or fifteen points higher than your target score. At that point, you’re officially “playing with a full deck.” Then you’ll keep doing practice tests, using those cards over and over again until they’re second nature to you. You won’t be shuffling through your card deck on test day–it will be second nature to you.

Can you see sustained and significant progress on the LSAT? Yes, you can!

What Am I Getting Myself Into?

Many LSAT courses claim that students can expect a ten-point gain if they attend the classes, read the book, and do the homework. That’s great for students who (only) want a ten-point gain, and who do well in classroom settings. I get the ones who want more than ten points, or need more than a lecture format. I get the gifted students and the ones with special needs.

Gaining ten points on the LSAT is good hard work, but it’s not that hard. It’s like running a five kilometer race (3.1 miles). Gaining twenty points on the LSAT is more like running a marathon.

Here’s what you need to go from couch potato to finishing a 5K race:

  • Commitment to the goal
  • A good pair of shoes and a water bottle
  • A realistic start–walk before you run!
  • Real rest between workouts
  • Feeling good about the progress you make each time you train

Here’s what you need to go from your first 5k to a marathon

  • 12-20 more weeks of training
  • Three to five solid workouts per week
  • One long run every week
  • Work up to running 50 miles each week
  • Hydration and nutrition
  • Intervals and speed training

I don’t promise that you can improve 20 points if you spend 20 weeks preparing for the LSAT, but I firmly believe that the average young healthy human can finish a marathon if they really want to, and the average intelligent college graduate can score above average on the LSAT if they work at it the way marathon runners do.

I can’t raise your LSAT score. Only you can do that; you do it by working and thinking. I can tell you how to work and how to think to raise you score more effectively.

Flaws: PowerScore’s Chapter on Causation

There are many LSAT questions that involve causal reasoning, which is significantly different from the conditional reasoning that makes up most of the rest of the test. PowerScore’s Logical Reasoning Bible squeezes in a chapter on causal reasoning between the chapter on “weakening arguments” and “strengthening arguments.” There’s a reason for that–a statement which might a perfectly valid conditional statement (“if the rooster crows, then the sun comes up”) could be a ridiculous causal claim (“the rooster crows, which causes the sun to come up”).

Noisy bird!

PowerScore identifies five situations which weaken a causal relationship. I have taken the liberty of turning them into an acronym:

  • R: Reverse causation
  • A: Alternate cause
  • C: Cause without effect
  • E: Effect without cause
  • S: Statistical errors

Let’s run through these, using our rooster example. Perhaps the rooster does not cause the sun to come up–instead, it is the early morning sunlight that causes the rooster to crow. That would be a clear case of reverse causation.

The problem with that explanation, as any chicken keeper knows, is that roosters start crowing long before the sky begins to get light. Maybe there is some kind of biological clock inside the rooster that tells it that 24 hours have passed. If so, that would be an alternate cause–something other than the sun itself that causes the effect.

If we wanted to prove that the rooster doesn’t really make the sun come up, we just need to get the rooster to crow in the middle of the night and see what happens. This happens to me now and then when we start something time consuming right around sunset. I have to grab my flashlight and go close up the chickens late at night. My roosters start crowing their heads off when I turn on the lights, and the sun stays put.  It’s hard to have a causal relationship if you you can have the “cause” (the rooster crowing) without the “effect” (the sun coming up). That’s a cause without effect situation.

Most of my students don’t even keep chickens–which means the sun comes up on them even though no rooster crowed.  That is an effect without cause situation.

PowerScore’s final category involves statistics. When we say, “The rooster crows and the sun comes up,” we oversimplify the situation. My roosters crow pretty much all day long. (That’s why we keep them well away from the house!) If we graphed all the times each rooster crows and plotted it against the sunrise, it would be obvious that the rooster has nothing to do with the sunrise. The reason I associate sunrise with roosters is that when those noisy birds wake me up I want to go make rooster soup! If I’m already awake, I just ignore their crowing. If I had good data instead of my very selective memory, I would never associate crowing with sunrise.

Flaw Questions and Bird-Watching

More students get more flaw questions wrong than anything else. (That’s because flaw questions are hard for many people, flaw answers are hard for most people, and there are lots of flaw questions on every test.) Every LSAT curriculum includes a chapter on flaws, but nothing that I have seen in print will enable a student to dramatically improve on flaw questions. That’s a pity, because flaws–more than any other question type–can be conquered with sufficient time and effort.

I want all my students to get every flaw question right every time. To achieve that goal, I start with the answer choices. Every LSAT flaw question has five different answers, and the overwhelming majority of those answers describe specific errors that any student can learn to identify with a little help and a lot of practice.

It’s a little like bird-watching. Here’s an example:

There’s a bird at my bird-feeder. It’s small bird, all black, gray, and white. There’s some white on its cheeks  but the top of its head and the underside of its chin is black.  I see plenty of them every winter, but the only time I’ve seen one in summer was up in Maine.

  1. Chickadee
  2. Nuthatch
  3. Flicker
  4. Junco
  5. Cardinal

Most readers can probably rule out a cardinal instantly, but the rest of the options are harder. Most readers are going to have to click the hyperlinks to look at the pictures before they can identify this bird. But once you know exactly what these five birds look like, it’s (fairly) easy to pick the right one from the list.

Once you know your flaws, you can eliminate wrong answers in a hurry.  In our bird example above, only two of those five birds are white and gray and black. One of the others is a dark gray and white, but there’s no white on the head so it isn’t an option. Of the two that really are white and gray and black, one is migratory and the other isn’t. Any decent bird-watcher could pick the right answer in about five seconds without ever needing to click on a hyperlink. I want you to be that fast (and that accurate) on flaw questions.

Flaws: Volume V Flaws

The following work-in-progress is a hyperlinked list of the ANSWERS to flaw questions in “10 Actual Official LSAT Preptests Volume V.” 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!

62-2-5: Childhood lead poisoning (p. 17)

  1. Statistical errors
  2. Circular reasoning
  3. Overlooked possibility
  4. Assumption
  5. Assumption

62-2-7: Flawed parallel pattern (p. 17) is fallacy of division

62-2-8: Space exploration (p. 18)

  1. Fallacy of composition
  2. Possibility v. Certainty
  3. Possibility v. Certainty
  4. Possibility v. Certainty
  5. Argument from ignorance

62-2-11: Athlete’s foot (p. 19)

  1. “Can cure” does not equal “always cures”
  2. Survey problem
  3. Assumption
  4. Overlooked possibility
  5. Assumption

62-4-9: Parallel flawed pattern (p. 30) is “if a husband is right-handed, the wife is probably right-handed; so if the wife is left-handed, the husband is probably left-handed.”

62-4-10: Moon of Jupiter (p. 30) [THIS NEEDS WORK!]

  1. Assumption (that a “necessary” condition is always necessary–this assumption is always true!)
  2. Overlooked possibility
  3. Assumption
  4. Overlooked possibility
  5. Assumption


  1. X


  1. X


  1. X


  1. X

Flaws: Logical Reasoning’s Biggest Challenge

Most of my students with accounts quickly discover that their highest study priority in logical reasoning should be “flaw” questions. With seven or more flaw questions per test and five confusing answers per question, most students will spend at least six minutes on LSAT day just trying to figure out what those flaw answers are supposed to mean. Every answer you don’t recognize consumes time, adds stress, and increases your odds of picking the wrong answer.

Students can improve both speed and accuracy by learning how to quickly and accurately recognize what the different flaw answer choices mean. The faster you can dismiss a wrong answer, the faster you can find the right answer and move on. A student who can quickly identify the wording used to describe common flaws should gain enough time to do at least two more questions in each logical reasoning section–and may be able to get more of the flaw questions right in the process. That can raise your score on test day significantly!

I have asked many students to study these flaw answer choices on  their own–with disappointing results. If you don’t know what the various flaws are, it’s really hard to figure out what these answer choices mean.  I have yet to find a commercially available LSAT text that enables the average student to quickly, confidently, and accurately identify the different answer choices.

They say it is better to light a single candle than to curse the darkness, so this series of posts is my attempt to light the way for a new generation of law students. I hope to identify every flaw answer choice in every “10 Actual Official LSAT Preptest” book. Here’s what I’ve done so far:


Flaws: Master Index


Master Index of Flaws

  1. Ad hominem
  2. Alternate cause
  3. Appeal to authority
  4. Appeal to emotion
  5. Appeal to the people
  6. Argument from ignorance
  7. Assumption
  8. Circular reasoning
  9. Correlation does not imply causation
  10. Equivocation
  11. Fallacy of composition
  12. Fallacy of division
  13. False dilemma
  14. Genetic fallacy
  15. Hasty generalization
  16. Internal contradiction
  17. Is/ought problem
  18. Mistaken most
  19. Mistaken negation
  20. Mistaken reversal
  21. No true Scotsman
  22. Numbers v. Percents
  23. Overlooked possibility
  24. Possibility v. Certainty
  25. Reverse causation
  26. Straw man
  27. Subjective/objective problem
  28. Survey problem
  29. Unrepresentative sample