Understanding LSAT necessary vs sufficient conditions

And…we’re back!

So, if my last two articles were a little too “back-to-basics” for you, you’re going to love this one.

We already talked about common LR topics and vocabulary, so now we’re getting into the nitty-gritty.

This time we’re digging into sufficient conditions, necessary conditions, and time.

Specifically, we’re talking about conditional statements here, or if/then as they’re sometimes called.

For example, if I eat Taco Bell for dinner, then I’ll be getting up all night to run to the bathroom.

So, in this case, the sufficient condition is considered the “if” and the necessary condition is considered the “then”.

If it makes it easier, think it terms of X and Y:
If x, then y.

If sufficient condition, then necessary condition.

Wouldn’t it be nice if it were just that simple? But, of course it never is. There are actually a lot of words that can be used in the X and Y slots.

Sufficient (X) Words include: All, any, every, if, in order to, the only, to be, when, whenever

Necessary (Y) Words include: depends upon, must, only, only if, only when, requires, then

Keeping up? Good.

Now here’s the confusing thing: these can be worded different ways to throw you off.

LSAT test makers can be real jerks sometimes!

We already covered the, If X, then Y phrasing but there’s much more sneaky way of wording this as well.

This is called the contrapositive and looks like this using the aforementioned Taco Bell.

If I’m not getting up all night to run to the bathroom, then I must not have had Taco Bell.

Need more examples? Fortunately for you I’ve got a bunch!

You can find some of those here ----> 

Also, I’m proud to say I have a very active and intelligent group of people who read my articles, and they’re sometimes kind enough to contribute in LSAT Diaries or other ways.

For example, Vicky gave her 2 cents on Necessary vs Sufficient Conditions, and I think you’ll find it quite helpful!

That about covers it for today.

Be on the lookout for my next article, where I’ll share some tips on formal vs. informal logic.

You got this!

Steve “The LSAT Spirit Guide” Schwartz

P.S. Here's that logical fallacies worksheet I promised (File --> Download As PDF). In my next article, I'll share the "answers."

P.P.S. If you’ve been studying for a bit and have some helpful strategies to share, you could be the next Vicky! Seriously, I’m always looking to improve the resources available to everyone, so feel free to reach out with any insights. If there’s a place for them, I'll be sure to add them.

Recommended Resources:

1. LSAT Courses
The best of my LSAT material with exclusive access to attend my Live Online LSAT Master Classes + Q&As, and on-demand video lessons you can watch anytime. Plus, LSAT study plans to keep you on track. Save hundreds of dollars with an LSAT course package.

2. Logical Reasoning Explanations
The explanations that should have come with the LSAT. These don't just fall back on "out of scope," but actually tell you why the wrong answers are wrong, why the right answers are right, and the easiest way to get the correct answer.

3. Logical Reasoning Cheat Sheet
Based on what I'd typically do in college: read what the professor emphasized and condense it all onto a single piece of paper. It gave me a quick reference, making things a lot less threatening and a lot more manageable.

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