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**Studying for the LSAT / Re: if and only if**

« **on:**May 13, 2005, 11:04:03 AM »

They are different. X if and only if Y means: X <--> Y. In other words, it's X --> Y *AND* Y --> X.

X only if Y means: X --> Y. Note the single arrow. With if and only if, the arrow works both ways.

X only if Y means: X --> Y. Note the single arrow. With if and only if, the arrow works both ways.