Diagramming Difficult Words on the LSAT

Diagramming Tips

The sun is out, barbeques and beach days are being planned, and people across the land are missing all of it because they’re staying indoors, studying for hours on end. The season of the LSAT is upon us. You might not get to experience much of summer, but there’ll be time enough for leisure in the park when you’re a handsomely-paid lawyer. Now is the time for LSAT study.

As you probably know by now, conditional statements are one of the most common things you’ll run across on the LSAT. At first, these can be terribly difficult to understand. One of the reasons for this is that there are so many different ways to express a conditional statement. The most basic form is “If A, then B,” but there are a number of ways to say the exact same thing; “All As are Bs,” “No As are not Bs,” “Being a B is required of being an A,” “Having A is sufficient for having B.” A huge part of improving your conditional reasoning skills is learning to recognize all the different permutations that these can show up in. Certain words can help you recognize which condition is sufficient and which is necessary. Words such as…

ONLY IF – When you see “only if,” you should take a second to thank the LSAT gods, because “only if” is super easy to diagram; whatever immediately follows “only if” is necessary. You don’t even need to think about it. Just put the part after “only if” on the right side. For example:

Only if you study hard will you do well on the LSAT.

What follows “only if?” “Study hard,” so that’s in the necessary:

Do Well LSAT → Study Hard

Really, that’s it. Memorize this, and you’ll never have any excuse to misdiagram another “only if” statement ever again.

ONLY – “Only” presents much more of a challenge than its cheap cousin “only if.” The way “only” works is that whatever it refers to is necessary. Sounds easy, but the hard part is figuring out exactly what “only” is referring to anyway. One thing that can help is asking yourself “only what?” What is the necessary thing they’re referring to? What do you have to have? For example:

The only way you can win a competitive eating contest is by eating hundreds of hotdogs every day to prepare.

Here, what is “only” referring to? Well, it’s referring to “way,” the way you could win an eating contest. But what is that “way?” Well, the way you would do it is by eating hundreds of hotdogs. That’s the only way you could ever win. So:

Win Eating Contest → Hundreds of Hotdogs Per Day

So remember, you’re looking what “only” is referring to. Because that is what will be necessary.

UNLESS/UNTIL/WITHOUT/EXCEPT – You should be able to rattle off these four words immediately at the drop of a hat, because, like with “only,” they’re a gift that makes diagramming incredibly easy. Whenever you see “unless,” “until,” “without,” or “except,” you can just replace them with “if not.” Seriously, that’s all you have to do. For example:

You can’t get in the bar without your ID.

“Without” immediately becomes “if not,” and you end up with:

You can’t get in the bar IF NOT your ID.

Which is now super easy to diagram:

NOT ID → NOT BAR

Or:

Unless you’re a millionaire, you’ll never go to space.

“Unless” just becomes “if not,” and you end up with:

NOT Millionaire → NOT Going to Space

If you haven’t memorized these yet, do so now. Start chanting “Unless, Until, Without, Except.” And it loudly.

So make sure to internalize all of these, and you’ll be on your way to mastering conditional statements. Mastering conditional statements will reap rewards all over the test, getting you significantly closer getting a great score and finally being done with this damn test.

8 Responses

1. Loic Anagho says:

Thank you very much. In need of better understanding of some of the wordings in LR. Will be reading your post. Very helpful.

2. logic man says:

Unless you’re a millionaire, you’ll never go to space.

“Unless” just becomes “if not,” and you end up with:

NOT Millionaire → NOT Going to Space

Isnt this wrong! When there is an UNLESS it becomes Necessary

Therefore (Space —-> Millionaire)

example.

Unless a person studies, he will not receive an A+. You negate the NOT (in he will not receive an A+)

A+ —–>Studies

• Greg Nix says:

You’ve got the logic exactly right, but you’re adding an extra step and diagramming the contrapositive.

Here’s the original:
Unless you’re a millionaire, you’ll never go to space.
NOT Millionaire –> NOT Space

Now flip it and negate both sides, and you get:
Space –> Millionaire
If you’re going to space, you must be a millionaire.

Same thing with the studying:
Unless you study, you will not receive an A+.
NOT Study –> NOT A+

Flip it, negate:
A+ –> Study
If you received an A+, you must have studied.

Here’s a whole post on diagramming “unless” that might be helpful: http://blueprintprep.com/lsatblog/logical-reasoning-advice/how-to-diagram-unless-lsat-logical-reasoning-questions/

• logic man says:

I think this way is more confusing b.c people know that UNLESS is a necessary condition which goes on the right side. It’s weird to write -millionaire –> -space b/c were so used to putting unless as necessary. :S

Unless you’re a millionaire, you’ll never go to space.

• Greg Nix says:

I can see why it’s confusing. Logically, the word ‘unless’ introduces a necessary condition. However, to diagram one of these statements, it is much easier to replace ‘unless’ with the phrase ‘if not.’ The term following unless is negated to form the sufficient condition, and the other term forms the necessary condition. Sounds complicated, so here’s another example.

The vacuum is not in the closet unless the umbrella is in the closet. Replace ‘unless’ with ‘if not’ and you get If the umbrella is not in the closet, then the vacuum is not in the closet.

NOT Umbrella –> NOT Vacuum
and contrapositive:
Vacuum –> Umbrella

Similarly, don’t think UNLESS a millionaire, think IF NOT a millionaire.
If you’re not a millionaire, then you’ll never go to space.

The way you’re thinking of it isn’t wrong, but just be careful about flipping structure and doing negations in your head, since if you mix things up you’ll end up with an inverse or converse fallacy.

3. logic man says:

ahh i do it backwards thats why your way seems confusing to me but it is right my mistake! b/c even if S —->M the contra is -M—–>-S

4. jose says:

with the word “until” how would you diagram this:
“The team will win the championship, unless he gets acquitted.

I get confused when the preceding words in the statement is not negative. Meaning I can easily diagram when I encounter this:

The team will not win the championship, unless he gets acquitted
NOT acquitted -> NO championship
Championship -> acquitted

Thanks.

• Greg Nix says:

Jose,

Here’s how you’d diagram “The team will win the championship, unless he gets acquitted”:

NOT acquitted –> Win
NOT win –> acquitted

It’s exactly the same concept; you just don’t need to negate the necessary condition.