## Assumption Question

Prepare for the LSAT or discuss it with others in this forum.
icobes

Posts: 13
Joined: Thu Jul 23, 2009 4:05 pm

### Assumption Question

For questions similar to PT 36, Section 3, Question 16, I always narrow it down to choices (A) and (D) but I never know which one to choose. I always guess, usually getting it wrong. So how do I tell if the question is looking for a necessary or sufficient condition? Could someone please explain this using question 16 that I mentioned above as an example?

Thanks so much!

yzero1

Posts: 185
Joined: Thu May 27, 2010 4:33 pm

### Re: Assumption Question

Looks like you're having trouble picking from a set of two reversed suff/necc relationships.

The stimulus goes like this: Reptiles incapable of making alterations in behavior -> incapable of complex reasoning.

The contrapositive of that statement is: capable of complex reasoning -> capable of making alterations in behavior.

This is exactly what (D) says (complex reasoning -> able to make changes in behaviour). If this were negated, then it would say "even if reptiles were capable of complex reasoning, they would NOT be able to make major changes in behavior". This would make it the conclusion fail because you just proved that reptiles can have complex reasoning yet at the same time not be able to make changes in their behavior. Thus, showing that a reptile cannot make changes in their behavior does not prove that they cannot have complex reasoning.

I would suggest diagramming the relationship in the stimulus if you're having trouble handling it conceptually. Also, use the negation test to see if the conclusion follows.

alanrickman

Posts: 10
Joined: Thu Nov 05, 2009 8:26 pm

### Re: Assumption Question

One of the best ways to think about this is to look at the wording withing each of the answers. In choice A, the scope of the assumption is very rigid (empahsis on the word "only" here). In choice D, there is emphasis on the word "sometimes." Since the stimulus deals with a rejection, that is the word "incapable" (which we can then translate to the word "never"), the effective "opposite" of this is "sometimes." Thinking about these types of questions in the scope of necessary and sufficient conditions can really lead to confusion (for me, at least). Generally, the "answer" is quite simple.

edit: the above poster explained this much better...ignore mine lol

jfb

Posts: 196
Joined: Tue Feb 03, 2009 1:26 am

### Re: Assumption Question

Answer choice d provides a situation that is necessary for the conclusion to follow. If choice d is not true, then the conclusion would not be valid.

A general rule, necessary assumption questions such as this, look for something that has to be true for the conclusion to follow. For justify and some strengthen questions, which are similar, you are looking for something that is sufficient to make the conclusion valid, but is not required.

3|ink

Posts: 7391
Joined: Wed Dec 16, 2009 5:23 pm

### Re: Assumption Question

"The conclusion follows logically if which of the following is assumed"

In this question type, you'd be looking for a sufficient condition. It's important to remember an important quality of sufficient conditions: If the sufficient condition is met, the necessary condition must be met. The only way you can make a logical deduction is by having a sufficient condition. In stimuli preceeding question stems like the one written above, you will typically be presented with an argument that lacks a sufficient condition needed to complete the argument. This isn't to say that the stimulus will be void of any sufficient conditions. There may be sub-arguments within the stimulus that are validly drawn, but the overall conclusion will be lacking a sufficient condition that would allow it to be a perfect argument. The main conlcusion will be flawed because it makes an inference without a sufficient condition. Your objective in these questions is to find the answer choice that would make the argument perfect.

Ug. I have to get off. Can someone please explain assumption questions to him?

jfb

Posts: 196
Joined: Tue Feb 03, 2009 1:26 am

### Re: Assumption Question

3|ink wrote:"The conclusion follows logically if which of the following is assumed"

In this question type, you'd be looking for a sufficient condition. It's important to remember an important quality of sufficient conditions: If the sufficient condition is met, the necessary condition must be met. The only way you can make a logical deduction is by having a sufficient condition. In stimuli preceeding question stems like the one written above, you will typically be presented with an argument that lacks a sufficient condition needed to complete the argument. This isn't to say that the stimulus will be void of any sufficient conditions. There may be sub-arguments within the stimulus that are validly drawn, but the overall conclusion will be lacking a sufficient condition that would allow it to be a perfect argument. The main conlcusion will be flawed because it makes an inference without a sufficient condition. Your objective in these questions is to find the answer choice that would make the argument perfect.

Ug. I have to get off. Can someone please explain assumption questions to him?

the question is "which one of the following is an assumption required by the herpetologists argument"

he would be looking for a necessary condition of the conclusion