**QUESTION TEXT:** Secondary school students achieve broad mastery of…

**QUESTION TYPE:** Sufficient Assumption

**CONCLUSION:** If students don’t achieve broad mastery, they aren’t being taught using appropriate methods.

**REASONING:** Students achieve broad mastery if they are taught with appropriate methods and they devote significant effort to their studies.

**ANALYSIS:** This is an unusually tricky sufficient assumption question. To get this right, you really need to draw it and see the flaw first. In fact I’m going to draw it like a logic game.

This is a *long *explanation. However, when I did this question myself, I did it rather quickly. The reason is that this process takes a long time to *explain, *but this process does not take a long time to *do. *

You should use this explanation to understand, but then practice the diagramming process on your own so that you learn it and can apply it quickly.

First let’s look at the conclusion. We need to get from lack of broad mastery to lack of appropriate methods:

Now let’s look at the evidence. If you have appropriate methods AND significant effort, you have broad mastery:

The contrapositive is that if you don’t have broad mastery, you’re missing appropriate methods or significant effort:

And this is where the flaw is. If we lack broad mastery, it’s possible we have appropriate methods, and the problem is that we lack significant efforts. Not good. We need to make it 100% certain that lack of broad mastery means no appropriate methods.

There are two possibilities when you lack broad mastery: ~~M~~ or ~~E~~. We can guarantee the conclusion by showing that either possibility leads to ~~M~~.

If we say that all appropriate methods lead to effort (M –> E), then this attaches on to the diagram as the contrapositive (~~E~~ –> ~~M~~):

Now this matches the conclusion. If we don’t have broad mastery, then we don’t have adequate methods, no matter which path we choose.

Note: My diagrams are just one letter. If you make long, confusing acronyms, your own diagrams will destroy you. I’ve seen this happen time and time again. Diagrams are just a tool. The real knowledge should be in your head. Pick one useful letter, and *remember *what the letters refer to.

Note: I didn’t do this diagram the first time I did this question. I solved this question with intuition. But following these steps will help improve your conditional logic, and there will be easier questions that you *can *solve up front.

___________

**CORRECT.**See the explanation above. This answer matches the addition statement I added to the diagram, and proves the conclusion. If this is true, then lack of broad mastery inevitably leads to lack of adequate methods.- This is a reversal of part of the evidence: broad mastery –> significant efforts.

We’re looking for something that tells us what happens if we*don’t*have broad mastery.

The “even if” part of this answer choice is meaningless fluff, it means that appropriate methods are neither sufficient nor necessary. - This tells us: broad mastery –> appropriate methods. That’s a reversal of the evidence from the argument, where appropriate methods were part of a sufficient condition for broad mastery.

Contrapositive of the answer:~~appropriate methods~~–>~~broad mastery~~.

Not helpful. We need an answer that tells us what happens if we*don’t*have broad mastery. It needs to b the sufficient condition: e.g.~~broad mastery~~–> [something useful]. - So? This was already implied by the stimulus. We only know that appropriate methods are a sufficient condition if they are accompanied by effort.
- This is the same as D. We already know this is true. Efforts are only sufficient if accompanied by appropriate methods.

**Free Logical R**easoning** lesson**

Get a free sample of the Logical Reasoning Mastery Seminar. Learn tips for solving LR questions

Great, thank you! This makes so much sense now, where previously I thought – I will never understand this question.

I’d say we can better characterize (B) as not being sufficient because it restates something we already know (one of A or B is not enough to establish C).

(B) is actually not quite a restatement of the premise since it’s structure is ~E –> ~BM. The premise’s structure is M + E –> BM. So, the answer choice is now making an additional, stronger statement about E –namely, that in its absence, there will be

nobroad mastery. That’s not something that we’re told by the premise.Wow, thanks so much, this is the clearest explanation of this question.

Are there other questions on tests that are similar to this one that you could provide ?? I feel like I’ve never seen this exact type before. And I’d like to practice so I can figure out a question like this with *intuition* next time, instead of plain getting it wrong and being all confused. Thanks!

There are three good ways to get better at questions like this one — to the point where you can often answer them using your intuition:

(1) Conditional Reasoning Drills: you can find these online and in the LSAT Hacks Course

(2) Drilling Sufficient Assumption and Necessary Assumption Questions, especially (or only) those that involve Conditional Reasoning. Start out by drawing the conditional reasoning chains for both the stimulus

andevery answer choice (and explain why the incorrect answers are incorrect using conditional reasoning)(3) Drilling questions from other question types that involve conditional reasoning using the same method described in (2)

I selected C because

C) ~M -> ~BM

combined with the conclusion

~BM -> ~M

makes the above relationship biconditional hence,

~BM ~M which always guarantees ~BM &~M or BM & M.

Is it wrong? Please help!

First, combining the answer with the conclusion doesn’t make a biconditional which can prove the relationship. Instead, you have to prove the conclusion. Let’s look at the correct answer, A now. Imagine if A is incorrect. If we assume that students are being taught with appropriate methods BUT it isn’t guaranteed that they will devote significant effort, then they will still not achieve broad mastery. Why? Because of the first premise:

If M and E –> B

The contrapositive is ~B –> ~M or ~E

This is the conclusion. This means if either M or E are missing, you won’t get B.

The problem with C is that it reverses the evidence. C says:

If B –> M, which incorrectly reverses the evidence.

In your explanation of C, you started out with ~M –> ~B, which is an accurate interpretation of C. But when you reverse it, it leads you to B –> M, which as show above, is inaccurate.

As well, keep in mind that for questions that ask for “conclusion can be drawn if X is assumed”, what you’re trying to do is to fill a gap between the premise and the conclusion. C completely disregards E.