Sufficient & Necessary Practice - “Only”

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Hey LSAT prep friends! I hope your weekend went well and you had a nice chance to take a break and relax with your friends and family. A new week is upon us, meaning ample time for more studying! Today I thought we could have some Sufficient & Necessary (S&N) review on “only” statements! Sounds fun right? Let’s begin.

As you know, the word “only” introduces the necessary condition of a S&N statement. So, if we have “Only A is B,” A is our necessary condition and B is our sufficient condition. Let’s look at the example below.

EXAMPLE 1: “Only those who are very weak-minded refuse to be influenced by literature.” –Cassandra Clare

Sufficient condition: “refuse to be influenced by literature.”

Necessary condition: “those who are very weak-minded”

We can rewrite this as “If one refuses to be influenced by literature, then they are very weak-minded.”

Let’s diagram!

Ex 1: RIL ==> VWM

not VWM ==> not RIL

See how simple that was? Let’s try another one.

EXAMPLE 2: “You will have the happiest or bitterest hour of your life only when you finally find yourself.” –Pable Neruda

Sufficient condition: “You will have the happiest or bitterest hour of your life”

Necessary condition: “when you finally find yourself.”

We can rewrite this as “If you have the happiest or bitterest hour of your life, then you have finally found yourself.”

Ex 2: HHL or BHL ==> YFY

not YFY ==> not HHL and not BHL

It’s important to remember that “only,” “only if,” and “only when” all introduce the necessary condition. These “necessary condition prompters” should not be clumped together with the notorious “the only.” “The only” will introduce the sufficient condition. We will have a thorough review of “the only” soon!

Hope that helped rev up your LSAT prep engines! Now get going with your study schedule for the day!

Happy Studying!

Updated on Aug 18, 2016