Sufficient & Necessary

Posted on

LSATMax is always working on making sure that you know all the techniques and strategies for each question type, but you are the one with the power over your LSAT prep. You must use the skills we teach you on the LSAT questions in front of you. And, it’s not just enough for you to use them, but you need engrain them into your mind so that soon they will become second nature to you. How does one accomplish this? Practice, people! Practice!

With this in mind, let’s do some Sufficient & Necessary practice right now!

1. All jellybeans contain sugar

JB ===> CS

not CS ===> not JB

Here we have our basic Sufficient & Necessary statement. If it is a jellybean, then it contains sugar. Contrapositive? If it does not contain sugar, it is not a jellybean. Easy.

2. No jellybean is made from all natural ingredients.

JB ===> not MANI

MANI ===> not JB

Remember that “No As are Bs” means that if something is an A, it cannot be a B. So could we have something that is not made from all natural ingredients and is not a jellybean? Yes, of course! We could have sour gummy worms! Remember that the necessary condition of the general principle and the necessary condition of its contrapositive existing together is a viable possibility.

3. Naz will eat either a gummy bear or a sour patch kid.

not EGB ===> ESPK

not ESPK ===> EGB

Here we have an example of our classic either/or sentence. Can it be true that Naz eats both a gummy bear and a sour patch kid? Absolutely! Remember, the necessary conditions are a viable possibility.

4. Naz will be malnourished only if she continues to eat candy.

NM ===> CEC

not CEC ===> not NM

Here we see our “only if” rule in action. Put an arrow through the “only if” and then whatever is to the left of the “only if” is the sufficient condition and whatever is to the right of it is the necessary condition.

Alright, so now you have to do the rest. Get back to your LSAT prep and practice, practice, practice! As you continue seeing different Sufficient & Necessary statements on your Logical Reasoning and Logic Games sections, you will find that the techniques and skills will soon become second nature to you!

Happy Studying!

Naz signature
Updated on Aug 18, 2016