GMAT Weaken CR: Reduce, Don't Destroy | OG | Mayan Settlements at Colha

If you are working through Weaken questions and keep eliminating the correct choice because it does not break the conclusion, the Official question that begins "The earliest Mayan pottery found at Colha, in Belize" is a good place to see why that happens.

There is a specific moment worth catching in Weaken questions: you read the correct choice, notice that it does not actually prove the author wrong, and move on because eliminating the choice feels justified at the time. And then you get to know that it was the correct choice. So what went wrong?

The standard a weakener has to meet is lower than it looks. A correct weakener brings in a new piece of information that reduces your belief in the conclusion, without challenging any premise. Reduces, not necessarily destroys.

The Question Setup

Let's see how this works in a question.

In this question, the earliest Mayan pottery found at a site in Belize is roughly 3,000 years old. Stone agricultural implements unearthed more recently at the same site are about 4,500 years old. Those implements resemble Mayan stone implements from a much later period, also found there, and their designs differ strikingly from the designs of implements made by other cultures known to have lived in the area in prehistoric times. The author concludes that Mayan settlements were surely present at the site 4,500 years ago.

The logic runs like this: these implements look Mayan and look like nothing else in the area, so Mayans must have made them, so Mayans must have been there.

So the correct answer needs to bring in new information that makes it less believable that Mayans were settled at the site 4,500 years ago.

The Correct Answer

The correct choice says that successor cultures at a given site often adopt the style of agricultural implements used by earlier inhabitants of the same site.

Notice what this choice does not do. It does not say Mayans were absent from the site. It does not say these particular implements were made by someone else. It does not even name the site or the Mayans. It states a general tendency.

Now trace what it does. If successor cultures often borrow the styles of those who came before them, then the 4,500-year-old implements could have been made by some earlier, non-Mayan culture, and the Mayans who arrived later could have adopted that style. That single possibility explains the resemblance without requiring any Mayan presence 4,500 years ago. The author's strongest piece of evidence now has a second explanation.

That is all a weakener has to do. The author was trying to convince you the conclusion is true. The weakener convinces you the opposite is also possible.

Also look at how the conclusion is worded: there were surely Mayan settlements. The author is claiming certainty. Against a claim that strong, a credible alternative explanation is enough to do real damage. You do not need to rule the Mayans out. You only need to show that the evidence no longer points to them alone.

The Habit This Builds

So when you are rejecting a choice in a Weaken question, ask yourself:

Am I rejecting this choice because it leaves the conclusion untouched, or because it does not fully disprove it?
Does this choice offer another explanation for the author's evidence?
After reading it, do I believe the conclusion a little less than I did before?

If the answer to the last question is yes, the choice is doing its job. Demanding more than that is one of the ways students talk themselves out of the correct answer.

One more reason to fix this habit now: it does not stay confined to Weaken questions.

In Evaluate questions, the correct answer is a question whose possible answers pull your belief in opposite directions, one raising it and one lowering it. Neither side has to settle the matter. If you are looking for an answer that proves or disproves the conclusion, you will reject the correct option there for exactly the same reason you rejected it here.
The same applies on Strengthen. A choice that makes the conclusion more believable does not have to establish it.

About This Series

This question is part of the Weaken Beginner Series, in which easy Official GMAT questions are used not to test what you know, but to reveal how you think. Each question targets a specific reasoning habit, one that shows up in a simple form on easy questions and a complex one on hard questions. If you are getting started with Weaken questions or if Weaken questions feel inconsistent for you, this series is built to show you exactly where the process is breaking down.

Solve the question on your own first. The reasoning you apply matters more than the answer you reach.

A Weakener Only Has to Reduce Your Belief, Not Necessarily Destroy the Conclusion

The Question Setup

The Correct Answer

The Habit This Builds

About This Series

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