LSAT Logical Reasoning Bible (2015) pg. 192-3

[dd170]

Hi,

I was working through chapter six and I continuously have trouble differentiating between the necessary and sufficient conditions.They seem so obvious, but at times really trip me up. Looking at both questions 3 and 10 on pages 192 and 193 I had this problem. The answer keys to the questions are on 195 and 198. For question 3 I do not understand why the race Saturday is necessary for having good weather and city approval....Wouldn't good weather and city approval be necessary for the race?

Same question with number 10- aren't the package arriving and the meeting getting arranged necessary to call the president? If you call the president, then it means those two things must have been done. However, if those two things are done, it does not necessarily mean you have called the president yet.


Please help explain.

Thanks!

[Dave Killoran]

Hi DD,

Thanks for the question! The difficulty you are having is very common, and it's come up on this Forum several times before. So, the good news is that it's something I've had a chance to address previously, and I can also tell you that in general it's not too tough to overcome

If my suspicion is correct, what's happening is that you are looking at each sentence in a real-world perspective and trying to figure out what would be most logical, as opposed to analyzing what the author is specifically saying. This is an easy and understandable trap to fall into, but it causes huge problems on the LSAT because authors are not always logical in what they say. The first way to overcome this is to focus less on figuring out how it would work in the real-world, and focus more on identifying the indicator words used by the author. Those indicators are road signs, and when present they immediately tell you what the author has said and how the conditions will work. To learn a bit more about this, please take a look at some of the prior posts I've made about this topic:

• http://forum.powerscore.com/lsat/viewto ... p=216#p216 (point #3 and after is what applies most to what's giving you trouble)
  
  http://forum.powerscore.com/lsat/viewto ... 6166#p6166 (focus on the discussion of indicator words in this post)

With those in mind, for a problem like #3, my analysis would look like the following:

• What is the conditional indicator? The word "if" is the big one, and you should almost think about that as if it is blinking in red neon Once I see that word, I know that what comes after it is sufficient (WG + AC), and then the last part is the necessary condition (RS). And in that way I see the relationship quickly and easily, and you might notice I don't even stop to think about how weather affects a race, etc. In other words, I ignore what I know or believe about those topics in the real world, and just use the language of the author to determine what was said.

Once you go through those, take a look again at some of the problems you asked me about, and let's see if that doesn't help resolve those. If it doesn't, definitely let me know and we'll walk through each one in detail.

Thanks!