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Q. Regarding Necessary Cause

lathlee
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In LR Bible since 2016, you guys added the concept of sufficient and Necessary Causes. I Think i got the mechanics of sufficient cause.(although it would be awesome if you guys can provide some example(s)

More importantly, can you provide an example of necessary cause? Especially in a likely context of Lsat Question stimul. If you guys can provide which prior lsat had necessary cause involving question(s), that would be even more awesome.


Thank you so much.
Adam Tyson
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I'll give it a shot, lathlee! A sufficient cause is, like a sufficient condition in any conditional reasoning relationship, one that absolutely guarantees a certain effect will occur. The effect is necessary in the presence of the cause. In our analysis of most causal relationships in the LR sections of the LSAT, we treat the argument as if the author thinks the cause is sufficient for the effect, unless he indicates otherwise (like by saying one thing CAN cause another, or that it contributes to the effect). A sufficient cause would look something like this:

Jumping into a swimming pool filled with water will cause you to get wet.

Here, the cause guarantees the effect - you must get wet if you jump in the pool. The cause is, by itself, sufficient for the effect.

A necessary cause, on the other hand, is one that must be present if the effect is present. That is, the effect guarantees the cause. For example:

If I am in a good mood during my morning meeting, it can only be because I had a large cup of coffee.

The effect (my good mood) guarantees that the cause occurred (I had my coffee). The cause is necessary in this relationship. Put another way, I could not be in a good mood at that meeting without having had the coffee. But the coffee is not sufficient for the good mood - I might have my coffee and still be in a foul mood during the meeting.

Does that clear up the difference for you? If not, you know where to find us!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
Follow me on Twitter at https://twitter.com/LSATadam
lathlee
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Thank you so much sir