CR # 3

Although many doubts have been raised as to the accuracy of age estimation for a recently found African artifact, all this criticism has no grounds. To estimate the age of the artifact, archeologists used a radiocarbon dating method known to be highly accurate in estimating the age of organic materials.

The conclusion above depends on which of the following assumptions?

A) Modern dating methods are generally more accurate than older dating methods.

B) Written records report that artifacts similar to the one recently found were being used at the time indicated by radiocarbon dating method.

C) The recently uncovered African artifact is made of organic material.

D) Some of the scientists who doubt the accuracy of the age estimations are very young.

E) Radiocarbon dating cannot accurately estimate the age of objects and materials that are more than 60,000 years old.

This is not a very hard question, but before you try to predict a correct answer, analyze the argument to see what was concluded and what evidence was offered to support that conclusion. The argument concludes that criticism has no grounds, that the age estimation was accurate. This conclusion is supported by a single piece of evidence: the radiocarbon dating method used is highly accurate in estimating the age of organic materials.

If you were careful, you noticed that the evidence was somewhat limited; specifically, the method was said to be accurate in dating ORGANIC materials. To conclude that the method was accurate for the African artifact, the argument must assume that the artifact was organic OR that the method effectively used for dating organic materials is equally effective when it comes to dating non-organic materials. The correct answer choice therefore must be an assumption that creates one of those connections.

A) Modern dating methods are generally more accurate than older dating methods. This choice is clearly irrelevant to the argument, since the one method discussed is not compared to any others. You can eliminate this option without further testing it.

B) Written records report thatartifacts similar to the one recently found were being used at the time indicated by radiocarbon dating method. This one may be tempting because such information, if added to the argument, would strengthen it. Remember, however, not every strengthening option must be assumed. Test this option by negating it to see whether it ruins the argument's logic.

• The criticism has no grounds.
• No written records report that artifacts similar to the one recently found were being used at the time indicated by radiocarbon dating.
• Radiocarbon dating is highly accurate for estimating age of organic materials.

Well, you can see that although adding this information might strengthen the argument, it is not information that must be assumed. Even if the information is not true, the argument could still be valid.

C) The recently uncovered African artifact is made of organic material. Correct. If you add this information to the argument, you strengthen it by connecting the stated evidence to the stated conclusion. If you negate this information and say that the recently uncovered African artifact is NOT made of organic material, then your evidence becomes irrelevant, as you know only that radiocarbon dating works for organic materials but have no idea whether it would have worked on the non-organic artifact.

D) Some of the scientists who doubt the accuracy of the age estimations are very young. Even if they all were very old, this would not change a thing, at least as long as you don't have information that links scientists' age and validity of their doubts.

E) Radiocarbon dating cannot accurately estimate the age of objects and materials that are more than 60,000 years old. You don't know the age estimated, so this information is irrelevant.

This concludes our first post on assumption questions, but we will continue this topic, examining the most common types of assumptions made by GMAT arguments and giving you some more practice questions.