How do you identify necessary and sufficient conditions?

[tyrionlannister]

I am having trouble identifying what the sufficient condition is and what the necessary condition is. With the exercise beginning on page 188, with the first few questions it seemed that the condition that came first in the phrase was the sufficient condition and the condition that came second was the necessary condition. However, that is not the case in nos. 7 or 10. I also do not understand how to solve the problem on p. 199.

[Jonathan Evans]

Hi, Tyrion,

Questions such as yours about conditional reasoning are more common than you might think!

We have a wealth of resources available to help further explain the subject, so I would like to refer you to some existing articles and posts that you will likely find helpful:

• Avoid Real World Interpretations and Follow the Language: http://forum.powerscore.com/lsat/viewto ... p=216#p216
  
  One More Look on what Sufficient and Necessary Means (this is key so that when indicators aren't present, we know what we're doing): http://forum.powerscore.com/lsat/viewto ... 6166#p6166
  
  The PowerScore LSAT Blog, Conditional Reasoning articles: http://blog.powerscore.com/lsat/topic/l ... -reasoning We write often about this concept, and there are over 20 articles here discussions all sorts of interesting conditional language and arrow relationships.

There are many more posts about this subject both on the forum and on the LSAT Free Help Area: https://www.powerscore.com/lsat/help/

With respect to numbers 7 and 10 from that exercise, there are excellent explanations on pages 193 and 195, respectively. For problem 7, it may be helpful to think about this in terms of what event will guarantee another event. The two events are (1) the park closes and (2) the sun goes down. Which one of these events guarantees the other?

The sun going down guarantees the park closes. Thus, the event/statement that guarantees the truth of another event/statement is the sufficient condition. The sun going down is sufficient to guarantee that the park closes.

• SGD PC

For problem 10, remember to pay attention to the conditional indicator words, in this case "only," which introduces a necessary condition.

• "Only a professional consultant..." means that "professional consultant" is necessary. What is the consultant necessary for? To solve the organization's problems.
  
  SOP PC

For the problem on page 199, could you please specify where and how you are having difficulty solving it? In the provided explanation, what does not make sense to you? This is a very challenging problem that requires students to parse dense and unfamiliar language and analyze conditional statements. It may be helpful to continue to work with the identification drill and conditional lessons to improve your mastery of these concepts and then return to this problem.

Please consult the resources outlined above and the explanations provided. Also, please reply and follow up with more questions about the specific concepts you find challenging.

I hope this helps!