Not sure what all those letters and arrows are that people draw for the LSAT? Watch this video on Sufficient and Necessary Conditions, fundamental to LSAT Logic.
Drawing LSAT Sufficient And Necessary Conditions
You've probably heard a lot about sufficient and necessary conditions on the LSAT. They're tough to get a handle on at first, but not that difficult once you get the hang of it.
A sufficient condition is "enough" to tell you that something else is true. Suppose I tell you that a CEO of a fortune 500 company is powerful.
Then if I tell you that Tim Cook is CEO of Apple, a fortune 500 company, you know something. Tim Cook is powerful.
A necessary condition is something that has to be true, when something else is true. "Powerful" is the necessary condition of the statement I just told you. If you find out that Marissa Mayer is CEO of Yahoo, then you know she is necessarily powerful. It can't be any other way.
A conditional statement has a sufficient and a necessary condition. A conditional statement is true 100% of the time.
So if I tell you that all Fortune 500 CEOs are powerful, don't look for an exception. Just assume that it's true. This isn't a good idea in real life, but it's what you have to do for the LSAT.
Drawing LSAT Conditional Statements With Arrows
It's complicated to try to keep track of several conditional statements. And LSAT logical reasoning questions often give you several conditional statements. So you should use a system of shorthand notation to represent them.
The system everyone has settled on has letters and arrows. Take the statement I gave above. Here's a good way to draw it:
C --> P
I prefer to stick to one letter, or two at most. Some people will try to add more letters, like this:
CEOF500 --> Pow
That quickly gets confusing. The letters should serve as a reminder of the statement, but they don't have to mirror every part of it.
Joining Conditional Statements To Form Deductions
If you have multiple conditional statements, you can often join them. Anytime the necessary condition of one statement matches the sufficient condition of another, you can put them together.
"Every CEO of a fortune 500 company is powerful."
"Everyone powerful is a little arrogant"
C --> P
P --> A
C --> P --> A
"Every CEO of a fortune 500 company is a little arrogant"
You could also draw this as C --> P --> LA, if you prefer to include the "little" in the statement about "arrogant".
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