Blueprint LSAT Prep's ongoing ask-an-instructor extravaganza Forum

[BP Robert]

Hi TLS -- a little primer from Blueprint for diagramming "only" statements on the LSAT.


If only the LSAT would stick with easy-to-diagram conditional statements like “if it’s a carrot, then it’s a vegetable”, or “if I get Mike Tyson’s tattoo, I’ll forever regret it”.

Alas, your Logical Reasoning section will rarely be quite so friendly. You’ll be nailed with parallel flaws, double negatives, “EXCEPT” questions and, most of all, lots of diagramming. So, to perfect your diagramming skills, we’re launching a series of articles that will cover some of the trickier elements of conditional statements.

Up first: “Only” Questions.

If memorization is your forte, then remember simply that “only” always introduces a necessary condition. As in “the only time you’ll see ‘only’ on LR is when it is introducing the proposition that is guaranteed by the sufficient condition.”

For those less memorization-inclined, however, let’s make this concept a little more intuitive. As an example, consider the following:

“Only Apple Inc. has the patent rights to rectangles with rounded edges”

What does the ‘only’ refer to in this case? It refers to Apple — meaning exclusively Apple; meaning none other than Apple; meaning that if it isn’t Apple, then it doesn’t have patent rights to rectangles with rounded edges. Essentially, if there exists something that has the patent, it’s necessary that that thing be Apple Inc. You would diagram it as:

patent rights to rectangles —> Apple Inc.

Unfortunately, not all questions are so straightforward. The most difficult involve conditional statements in which the referent (that which is referred to by ‘only’) does not immediately follow the word ‘only’. For instance:

“The only city that requires marijuana dispensaries to provide free weed to indigent patients is Berkeley”.

Tricky. Here the referent does not immediately follow the ‘only,’ so it can be a little more difficult to locate the necessary condition. But if we rephrase the conditional statement, it’s clear that it is necessary to be Berkeley in order to be a city with this policy. To say that having this policy is necessary in order to be Berkeley is 1. very silly and 2. the fallacy of the converse.

A little tip that has always worked well for me: I only (wink wink) diagram “only" statements in the contrapositive. For those unfamiliar with this term, it describes the relationship between “if A then B” and “if not B then not A” (the contrapositive being the latter). So when I diagram the above conditional I think of it in terms of:

“If it’s a city other than Berkeley, then it doesn’t require dispensaries to provide free weed”.

Thus, “not B —> not FW”

Tinker around with this a bit, and figure out what approach will make you the most comfortable, accurate, and efficient on test day. To get your mind working, check out the following examples.

The only bad pie is rhubarb pie.

Rhubarb pie is the only bad pie.

Both of these statements are diagrammed:

BP —> RP

This is because in both cases the “only” refers to that godforsaken nadir of pastries that is rhubarb. It is the limiting condition of the sentence -- the property upon which badness rests.

Here’s another:

Only Kobe Bryant compares to Michael Jordan as a basketball player.

The only basketball player who compares to Michael Jordan is Kobe Bryant.

As with the previous example, both of these are diagrammed:

CMJ —> KB

This is because the “only” refers to the Black Mamba. He’s necessary to make comparisons to Michael Jordan.

If you’re struggling with diagramming “only” statements, then take solace in the fact that you are not alone. Many find them difficult. However, as long as you keep in mind that you’re looking for what the “only” refers to, your 'only' (last one, I promise) concern going into the LSAT will be how to celebrate after.

[BP Robert]

Welcome to our ongoing series on the more nefarious elements of diagramming.

Topping the agenda today are “unless” questions. These are much more straightforward than the “only” conditionals we reviewed last week. Unlike “only” questions, which require one to search for the referent, “unless” questions have a more standardized approach. Consider the following:

“Unless I just brushed my teeth, you’ll find me sipping a cold glass of orange juice”

What does this mean? It tells us that, in all cases where I haven’t just finished brushing my teeth, I’ve got a tall glass of nature’s goodness by my side. To simplify: if I have not just brushed, then I’ve got OJ. Look diagrammable?

Sure does. We have our best two indicators — if and then — followed by a clear sufficient and necessary condition. Our conditional diagram should look something like:

not JB —> OJ

And if we take the contrapositive? Flip it, negate each side, and we have:

not OJ —> JB

Since I am without OJ, we know — on the basis of the original conditional — that I must have just brushed. As such, we see that the term “unless” introduces the necessary condition.

This example illustrates a nice little maneuver. “Unless,” in terms of logical structure, equates to “if not.” Meaning that “unless I just brushed my teeth,” “unless the sky falls,” and “unless my watch is incorrect,” equates to “if it is not the case that I just brushed my teeth,” “if it is not the case that the sky falls,” and “if it is not the case that my watch is incorrect,” respectively.

One more example to drive it home. 

“Unless I finish my LSAT homework, I won’t go out tonight”

To solve this self-serving example, just slap an “if not” in place of the “unless” as we practiced. Your diagram becomes:

not FLH —> not GOT

The contrapositive being, “if I go out tonight, then I must have finished my LSAT homework.” Your contrapositive diagram should look like this:

GOT —> FLH

I have one further tidbit of excellent news. This same “if not” rule applies to “until,” “without,” and “except,” as well. Meaning that “until I find a spoon I can’t eat my soup” equates to “if it’s not the case that I find a spoon, then I can’t eat my soup.” You’ll see these questions popping up quite frequently in your LSAT studies and on the test, so it’s a key skill to master.

The take away for this week is that, if you see “until,” “unless,” “except,” or “without” embedded in your LR question, then you’ve encountered a necessary condition. The most efficacious way to diagram these statements is to simply swap the “unless” for an “if not,” and diagram that negation. Unless you forget this method, you’re 180 bound.

[BP Robert]

Hi all,

Check out this blog post on diagramming and identifying necessary statements!


In case you hadn't already noticed, understanding and manipulating conditional statements is key to success on Logical Reasoning questions. If you don’t master this skill, then your target score will elude you (ya see what I did there?).

In our ongoing series we’ve covered many of the trickier types of conditional statements, but today we’re going to bring it back to basics with identifying the necessary condition through what we at Blueprint call “indicator words.”

This skill is fundamental in the sense that it’s necessary (dry puns abound) in order to get your diagramming off the ground. If the necessary and sufficient conditions are misinterpreted and thus diagrammed incorrectly, transitive chains will be missed, sufficient stacks will go unnoticed, etc., etc. Most common, perhaps, is confusing which of two statements in a sentence is the sufficient and which is the necessary. For example:

“If you clap your hands, Spot will bark.”

This is pretty straightforward. As many of you will have noticed, we have a sufficient condition followed by a necessary, and our diagram looks like this:

CH —> SB (Clap Hands Spot Barks)

But what about when the structure is not so clear? Consider the following:

“Spot will bark if you clap your hands.”

Some students are inclined to think that this is also a sufficient condition followed by a necessary, and diagram it as such:

SB —> CH (Spot Barks  Clap Hands)

This is, of course, incorrect. This diagram is actually the converse of the sentence given, and means, quite absurdly, that “If Spot barks, then you clap your hands.” Spot barks at lots of things — shadows, mailmen, that fine poodle down the street — so we know that this is not a proper representation of the original conditional statement. This sort of confusion can throw a question off track entirely, so to avoid it we look for indicator words.

“Then” is the canon of necessary indicators, to which we compare all others and below which all others are situated. Lucky for us, it comes up quite often on the LSAT as “If the iron is hot, then don’t touch it,” or “if you lose your dentures then you must eat soup.” Other common terms include “requires,” “necessitates,” and “must.”

While there are some relatively obscure terms that have the same meaning (“precipitates” and “yields,” for example), the LSAC’s goal is to beat you with logic, not with vocabulary. Thus, rarely will you see a question lexiconically obfuscated so as to be inimical. Focus instead on finding the referent of the necessary indicator, and thereby accurately identifying and diagramming the conditional.

[BP Robert]

Stay tuned for this week's post on diagramming and identifying sufficient conditions!

[BP Robert]

Some useful tips for diagramming "No" statements!

With a scurry and dash, a dodge and a slash, the No Ninja appears on the scene. Or: There She Blows, No Torpedoes the Necessary. Maybe, I don't know… Calamatizes the Consequent, Foils the Following, what have you. 

All of these mnemonics illustrate a very simple but highly effective tool for diagramming “No” statements on the LSAT. These are common conditionals, and they can come in many forms:

No mathletes have girlfriends.
None of the above are correct.
Neither of them are getting her number.
No one who dislikes Star Wars can be my friend.

etc, etc. The important thing to note here is that each of these statements posit that there is no overlap between the two groups. The group of “Mathletes” does not overlap with the group of “having a girlfriend,” for example.

Thus, to diagram, we show that if you are a member of one of these groups, you are not a member of the other. Just that simple. If you are in group A, then that means you are necessarily not in group B. 

A —> not B
the contrapositive, of course, is
B —> not A

Going back to picking on mathletes, we would say that
M —> no GF
and the contrapositive would be
GF —> not M

Meaning that if you are a mathlete, then you don't have a girlfriend; if you have a girlfriend, you cannot be a mathlete.

We refer to this procedure as the “No Torpedo” and “No Ninja” to reinforce the idea that if you belong to the sufficient group then you “torpedo” or “slash” the necessary group. If you too coo’ for punny memory tricks, remember simply that because the groups do not overlap, belonging to one is sufficient to conclude that you necessarily cannot belong to the other.

[BP Robert]

As promised folks: Sufficient Conditions!


No discussion of conditional statements would be complete without a thorough review of sufficient conditions, the topic of today’s post in our ongoing review of diagramming LR questions.

Simply put, the sufficient guarantees the necessary. As long as the sufficient condition is satisfied, the necessary must follow. For example:

“If you study hard, then you’ll do well on the LSAT.”

To illustrate this relationship, we’ll want to diagram the above with the sufficient condition leading to the necessary condition, in the form of:

Suff. —> Necc.

Thus, for this particular conditional statement, we would diagram:

SH —> DW (Study Hard —> Do Well)

So what happens if we satisfy the sufficient? Well, if it is in fact the case that we studied hard, then we know based on the conditional above that we’ve triggered the necessary, and that it is also the case that we will do well on the LSAT.

This particular sentence employs our favorite indicator word for sufficient conditions: “if.” “If” is a great tip-off that we’re looking at the sufficient condition. Its counterpart, “then,” indicates the necessary. The order in which “if” and “then” (or their equivalents) appear is not important; what matters is the Suff. —> Necc. structure. For instance:

“I’m not going out with you if you’re wearing that fedora.”

This sentence actually has the sufficient condition following the necessary, unlike in the last example. But we wouldn't diagram the statement in that order because the sufficient is still triggering the necessary, not the other way around. Thus, recognizing that the “if” is giving us the sufficient condition, we diagram:

WF —> not GOWY (Wear Fedora —> not Going Out With You)

Keeping the right order is essential. The reverse, known by Logic Geeks the world over as the “Converse Fallacy,” is 1. invalid, 2. produces a non-representative diagram, and 3. is typically frightfully absurd.

“If you’re a dog, then you’ve got a tail.”

The above should be diagrammed:

D —> T (Dog —> Tail)

The converse fallacy would then be T —> D, which reads “If you have a tail, then you’re a dog.” But I can’t play fetch with my iguana, and there are numerous odd Youtube videos displaying human caudal appendages, so this is clearly not true. 

Accurate identification of the sufficient and necessary statements is absolutely key for diagramming, but it doesn’t have to be too difficult. Even in the absence of familiar indicator words, reframing the statement as an “if-then” conditional will be sufficient to guarantee your success.

[BP Robert]

A word of advice for those of you deciding whether or not to take the September test:

1. Take a practice test (obvs). Hold your feet to the fire and do it under times conditions, just like the actual LSAT.

2. Take a practice test untimed. At your own pace, work thru the test but employ the same methods you would under timed conditions.

3. Compare your scores.

If your untimed test is around your target score, but your timed is lacking, then that may be an indication that you have the skills down and just need to worry about drilling to get faster. Do so; it's more than likely that you can get your time up in these next five weeks.

If your score on the untimed test is also much below your target score, that'd suggest that your fundamentals require some fine tuning, prior to your speed-up practice. If you're in the same position a couple weeks from now, I might advise that you save your 180 for December.

Best of luck.

[sfoglia]

A word of advice for those of you deciding whether or not to take the September test:

1. Take a practice test (obvs). Hold your feet to the fire and do it under times conditions, just like the actual LSAT.

2. Take a practice test untimed. At your own pace, work thru the test but employ the same methods you would under timed conditions.

3. Compare your scores.

If your untimed test is around your target score, but your timed is lacking, then that may be an indication that you have the skills down and just need to worry about drilling to get faster. Do so; it's more than likely that you can get your time up in these next five weeks.

If your score on the untimed test is also much below your target score, that'd suggest that your fundamentals require some fine tuning, prior to your speed-up practice. If you're in the same position a couple weeks from now, I might advise that you save your 180 for December.

Best of luck.

This is great advice. Thank you.

[BP Robert]

My pleasure sfoglia! Good luck.

[BP Robert]

Cute and cuddly “A must come before B” rules are often perceived as cherished Logic Games instructions. It makes sense; they’re simple, absolute, and easily diagrammed. They’re also more intuitively digestible than some of our more complex Logic Games rules. 

But digesting complex carbs gives you fuel, and simple carbs give you a beer belly. Similarly, complex LG rules often unlock the game and propel you through the questions, whereas “A before B” rules… make you fat… (shush, no analogy is perfect). 

One of the most useful complex relationship comes in the form of an exclusive disjunction. You remember these from Logical Reasoning: “Bubba buys either laundry detergent or a whole new wardrobe, but not both.”

For Logic Games, this is expressed in the form of “Either A comes before B, or B comes before C, but not both.” These rules, initially, should be written like this:

A — B
or
B — C
but not both

Be not afraid, for there are deductions to be had. 

These are essentially conditionals; if one thing happens, then the other cannot happen. Let’s take the first relationship: A — B. Because of the “but not both,” we know that if A precedes B then it cannot be the case that B precedes C. In a One-to-One Ordering Game, that means that, in order to ensure that B does not precede C, we must have C precede B (because they cannot occupy the same space).

That’s huge for us. We know that both A and C precede B, so we should be diagramming with branches to reflect this relationship. The same goes for the other disjunct; if B comes before C, then we know that B must come before A.

Having done this, we’re left with a rule implying that either A and C both precede B, or else B precedes both A and C. Breathtakingly beautiful binary branches to better our brain-teaser.

So much for Ordering Games. This rule also appears, however, on Grouping Games. Let’s consider an In-and-Out Grouping Game. If we’re selecting from among eight super heroes to create a five person Justice League delegation, we might say that either Superman or Batman must be selected. But not both; that would be overkill.

Just like with Ordering Games, we have to make a deduction. If Superman is in, then what do we know? We know that, based on our “but not both” rule, Batman must be out, and vice versa. If, for example, we have another rule that “If Batman is not in the delegation then Wonderwoman must be,” then this initial deduction will be very useful in allowing us to make a chain of rules (if Superman is in then Batman is out and Wonderwoman is in).

The trick is to look at these rules not as a bigger challenge, but as a bigger and better key. They don’t just lead to discrete deductions; often you’ll find that the LSAC has hidden the whole solution behind these complex relationships, providing an extra incentive for you to go beyond simply transcribing the rules.

For more practice, check out the October 1993 Test, Game 2.

[flash21]

looking for multiple opinions on this, I'm writing the lsat in december, when should I begin doing PT's consistently?

[BP Robert]

I'd actually suggest that you wait a good bit before running consistent PT's. Right now your focus should be on the fundamentals -- the PT's come after because at this stage they aren't particularly useful.

If you're taking the December LSAT I'd suggest you take a PT sometime soon to set a benchmark, but then stick mostly to learning and drilling until around late October/early November. Maybe take two or three more practice tests in that span of time. At that point, you'll want to start taking PTs more regularly (I typically suggest two per week, if possible).

The basic idea is that you don't want to be practicing out of form -- wait until you've developed the skills.

Best luck.

[flash21]

I'd actually suggest that you wait a good bit before running consistent PT's. Right now your focus should be on the fundamentals -- the PT's come after because at this stage they aren't particularly useful.

If you're taking the December LSAT I'd suggest you take a PT sometime soon to set a benchmark, but then stick mostly to learning and drilling until around late October/early November. Maybe take two or three more practice tests in that span of time. At that point, you'll want to start taking PTs more regularly (I typically suggest two per week, if possible).

The basic idea is that you don't want to be practicing out of form -- wait until you've developed the skills.

Best luck.

Hey Rob, I've been studying for about a year now.

I did a pt a few weeks ago, got a 164. does this change anything?

[BP Robert]

Well first of all, congratulations on the score. That's a very good place to be at this point in your studies.

It does change my response just a bit, because it demonstrates that you're already forming a strong grasp on the material. As a consequence, you won't need quite as much time to drill and practice fundamentals. So I would say that most of what I said above still stands, but err on the side of sooner (eg when I say "late Oct/early Nov," perhaps take it to mean "late Oct").

If, over the course of September, you start to feel really comfortable with the concepts then maybe even start taking PTs in early October.

[flash21]

Well first of all, congratulations on the score. That's a very good place to be at this point in your studies.

It does change my response just a bit, because it demonstrates that you're already forming a strong grasp on the material. As a consequence, you won't need quite as much time to drill and practice fundamentals. So I would say that most of what I said above still stands, but err on the side of sooner (eg when I say "late Oct/early Nov," perhaps take it to mean "late Oct").

If, over the course of September, you start to feel really comfortable with the concepts then maybe even start taking PTs in early October.

Cool - thanks. I just want to make sure I get enough PT's in. I started from a 139 so there is always this bit of insecurity with PT's because the last time I attempted PT's which was so long ago I remember getting destroyed on them. I guess I want to make sure my PT confidence is up there. Do you think 2 or 3 a week is best?

[Lacoste]

Well first of all, congratulations on the score. That's a very good place to be at this point in your studies.

It does change my response just a bit, because it demonstrates that you're already forming a strong grasp on the material. As a consequence, you won't need quite as much time to drill and practice fundamentals. So I would say that most of what I said above still stands, but err on the side of sooner (eg when I say "late Oct/early Nov," perhaps take it to mean "late Oct").

If, over the course of September, you start to feel really comfortable with the concepts then maybe even start taking PTs in early October.

Cool - thanks. I just want to make sure I get enough PT's in. I started from a 139 so there is always this bit of insecurity with PT's because the last time I attempted PT's which was so long ago I remember getting destroyed on them. I guess I want to make sure my PT confidence is up there. Do you think 2 or 3 a week is best?

Wow Congrats. When did you start prep-ing and when do you plan on taking the lsat? I am in a similar situation (diagnostic low)

[flash21]

Well first of all, congratulations on the score. That's a very good place to be at this point in your studies.

It does change my response just a bit, because it demonstrates that you're already forming a strong grasp on the material. As a consequence, you won't need quite as much time to drill and practice fundamentals. So I would say that most of what I said above still stands, but err on the side of sooner (eg when I say "late Oct/early Nov," perhaps take it to mean "late Oct").

If, over the course of September, you start to feel really comfortable with the concepts then maybe even start taking PTs in early October.

Cool - thanks. I just want to make sure I get enough PT's in. I started from a 139 so there is always this bit of insecurity with PT's because the last time I attempted PT's which was so long ago I remember getting destroyed on them. I guess I want to make sure my PT confidence is up there. Do you think 2 or 3 a week is best?

Wow Congrats. When did you start prep-ing and when do you plan on taking the lsat? I am in a similar situation (diagnostic low)

Thanks man. Its been ridiculously challenging. I started prepping last summer, tried to prep during my undergrad year ( I wanted to write in Sept, then december, never got to write either, was pt'ing too low) , so I tried to retain my knowledge I learned in the summer in the school year and began drilling hard again this summer. So I guess its been like a year. Planning to write in December this year.

What was your diagnostic?

[BP Robert]

Well first of all, congratulations on the score. That's a very good place to be at this point in your studies.

It does change my response just a bit, because it demonstrates that you're already forming a strong grasp on the material. As a consequence, you won't need quite as much time to drill and practice fundamentals. So I would say that most of what I said above still stands, but err on the side of sooner (eg when I say "late Oct/early Nov," perhaps take it to mean "late Oct").

If, over the course of September, you start to feel really comfortable with the concepts then maybe even start taking PTs in early October.

Cool - thanks. I just want to make sure I get enough PT's in. I started from a 139 so there is always this bit of insecurity with PT's because the last time I attempted PT's which was so long ago I remember getting destroyed on them. I guess I want to make sure my PT confidence is up there. Do you think 2 or 3 a week is best?

Good question. I probably wouldn't recommend more than two per week at this point/in Oct -- definitely no more than three. As we head into late Nov/early Dec three might become appropriate if you're not yet where you'd like to be. Generally, however, I think two per week is a good goal.

[Tyr]

Hello,
I finished the BP games book earlier this month and I was just doing some review drilling. For some reason, PT12 S2 G2 (canoe trip) is giving me a lot of trouble. I've looked up explanations online, and everywhere I look, the assumption is made that each group has 3 people (at least 1 adult and 1 or 2 children). If I include this assumption, the game isn't a problem, but I don't see where people are getting that assumption. What am I missing?

Thanks!

[nlee10]

Hello,
I finished the BP games book earlier this month and I was just doing some review drilling. For some reason, PT12 S2 G2 (canoe trip) is giving me a lot of trouble. I've looked up explanations online, and everywhere I look, the assumption is made that each group has 3 people (at least 1 adult and 1 or 2 children). If I include this assumption, the game isn't a problem, but I don't see where people are getting that assumption. What am I missing?

Thanks!

Hey! I just did this PT yesterday. In the main stimulus right before all the conditions, it says the assumption "three canoeists each". Maybe perhaps you just misread the text but that definitely made the game much more easier.

[Tyr]

Hello,
I finished the BP games book earlier this month and I was just doing some review drilling. For some reason, PT12 S2 G2 (canoe trip) is giving me a lot of trouble. I've looked up explanations online, and everywhere I look, the assumption is made that each group has 3 people (at least 1 adult and 1 or 2 children). If I include this assumption, the game isn't a problem, but I don't see where people are getting that assumption. What am I missing?

Thanks!

Hey! I just did this PT yesterday. In the main stimulus right before all the conditions, it says the assumption "three canoeists each". Maybe perhaps you just misread the text but that definitely made the game much more easier.

Wow, I can't believe I missed that. Lesson learned - don't do drilling before 6:00 AM, it makes your life a lot more difficult.

Thank you so much!

[BP Robert]

Never before six. Glad we got that solved:)

[dmw88]

I'm from a school ranked in the 40's on US and news, i have a 4.0 and fairly strong softs but a 167. I am applying early decision to NYU but i'm writing the September exam. Should i wait until i get my score to apply early decision? Or should i send in everything now (i have most of the application done and my two recommendations are in). Or should i wait until later? If i send everything in now, can i send my september score while they have my application? Would love to hear your thoughts!

[nlee10]

Dear Blueprint/TLSers,

LR Studying
I will be taking a Blueprint live course for the DEC exam that runs late September-Dec. In terms of PT resources, I've only used up some of the early ones (in the 10's), PT 52, and the free June 07 one. I be starting the Manhattan LR book this week. Because there are 4 weeks until the start of the course, should I purchase the Cambridge LR packets by Q-types (PT 1-38) for drilling with the Manhattan? I figure since those are the older questions, some may not be relevant, but most will provide for good drilling.

I can then use the PT 41-60 packet during the prep course to gain exposure to the newer questions. I believe the 6 proctored exams from the course will be PT's later than 60 so there would be no overlap.

[BP Robert]

I'm from a school ranked in the 40's on US and news, i have a 4.0 and fairly strong softs but a 167. I am applying early decision to NYU but i'm writing the September exam. Should i wait until i get my score to apply early decision? Or should i send in everything now (i have most of the application done and my two recommendations are in). Or should i wait until later? If i send everything in now, can i send my september score while they have my application? Would love to hear your thoughts!

Hi DMW,

I think this may be a question for the admissions staff. They definitely won't tell you what's best strategically, per se, but the important question is whether or not their ED admissions are rolling. If they are then go ahead and submit your application, and include your updated score when it arrives mid-October.

If they are not rolling then there's no need to get your application in early. Go ahead and wait until you get the results of your September test.

I tried to find this information online but was unsuccessful, so try dropping it by admissions.

Best luck in September and admissions.