Free LSAT Course > Logical Reasoning > LSAT Formal Logic

There’s no avoiding that you need to learn some formal logic before tackling the LSAT. No worries; this will be about the easiest and most intuitive formal logic course ever made. We’ll even have interactive games coming in March (the Formal Logic course is currently under construction and should be finished by February).

The most basic logic rule is the Conditional (which is just a phrase like A → B).

1. Followers:

If A, then B.

If James competes, then Macro must go to the race as a coach.

Translate Phrases Into Conditionals

The item on the left in an If… then… statement is called the Sufficient and the one on the right is the Conditional. They bury these conditionals in convoluted language. It’s rarely stated bluntly as “if… then….“:

Sufficient flag words
If
When
People who
In order
All
Any

Necessary flag words
Then
Only
Must
Unless
Without
Except

Next LSAT: March 30th

Translate: Each, If, Every, Any

If every member of a group has a trait, then you can just do group trait.

All A’s are B’s is the same thing as A → B.

All dogs are mammals is equivalent to dog → mammal.

Every person who has gone to Yosemite never forgets it.

Goes to Yosemite → does not forget.

Whenever I speak to my boss I get nervous.

Speak to boss → gets nervous

Any LSAT student wants to master formal logic.
LSAT student → want to master formal logic
abbreviate: LS → WMFL

“If you can dream it,
you can do it.”

-Walt Disney

Diagram of Quote

 

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“A person is not old until they let regrets
take the place of their dreams.”

John Barrymore

Diagram of Quote

 

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Translate: Only / Only If

The trick with only is now the first sometimes phrase goes into the Necessity (translate from right to left).

Only coffee can get Ricky up in the morning.

Ricky up → coffee

Ricky will go to the party only if Jenny does.

Jenny → Ricky

Only dogs bark at vacuum cleaners. 

bark at vacuum cleaner → dog

“It is only the ignorant
who despise education.”

-Publilius Syrus

Diagram of Quote

Despise education → Ignorant

Diagram of Quote

Truth → Music
T → M

No / None

Meet the tilde: ~
That squiggly line (~) or a slash through symbolizes the opposite or an inversion.
In this course we use both the tilde and the slash because you’ll see both versions in different LSAT courses.

No human has stepped foot on Mars.

Human →  ~SFM
(SFM symbolizes “stepped foot on Mars.”)

None of the canned jellybeans are purple.

CJs →  ~purple
(CJ abbreviates “canned jellybeans.”)

No Great White Sharks are vegetarians.

GWS →  ~vegetarian
(GWS abbreviates “Great White Shark.”)

Never

You’ll typically use the ~ symbol in “never” statements.

“Never interrupt your enemy when
he is making a mistake.”

-Napoleon Bonaparte

“A smooth sea never made
a skilled sailor.”

-Franklin D. Roosevelt

“If you can’t beat them, join them.”

“If you can count your money,
you don’t have a billion dollars.”
-J. Paul Getty

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Next LSAT: March 30th