Question

Normal full-term babies are all born with certain instinctive reflexes that disappear by the age of two months. Because this three-month-old baby exhibits these reflexes, this baby is not a normal full-term baby. Which one of the following has a logical structure most like that of the argument above? (A) Because carbon dioxide tums limewater milky and this gas is oxygen, it will not turn limewater milky. (B) Because no ape can talk and Suzy is an ape, Suzy cannot talk. (C) Because humans are social animals and Henry is sociable, Henry is normal. (D) Because opossums have abdominal pouches and this animal lacks any such pouch, this animal is not an opossum. (E) Because some types of trees shed their leaves annually and this tree has not shed its leaves, it is not normal.

Short answer

The argument in option (D) matches the original argument's logical structure.

Step-by-step solution

Understand the Argument Structure

The original argument states that if a normal condition disappears by a certain time (reflexes in full-term babies by two months), and the condition persists beyond that time (three-month-old baby still has reflexes), then the subject must not belong to the normal category (not a normal full-term baby). This can be summarized as: If a trait disappears by age x in normal category, and subject exhibits trait past age x, then subject is not in the normal category.

Analyze Each Option

We will break down each option to see if it follows the same logical structure as the original argument. - (A) If limewater turns milky with carbon dioxide and this is oxygen, it will not turn milky. This does not match as it discusses different outcomes, not category belonging based on trait persistence. - (B) Apes cannot talk, and if Suzy is an ape, she cannot talk. This presents a different structure, as it doesn't concern a trait disappearing or persisting past a normal point. - (C) Humans are social animals, and since Henry is sociable, he is normal. Again, this relates to category based on traits but does not involve persistence past a time frame. - (D) Opossums have pouches, and if this animal does not have a pouch, it is not an opossum. This matches as it concerns a defining trait that, if absent, means the subject is not in the normal category described. - (E) Since some trees shed leaves and this tree hasn't, it's not normal. Relates to a lack of a trait being a sign of not normalcy, not quite matching as it doesn't involve all entities of a category (only 'some').

Determine the Correct Answer

Option (D) matches the structure most closely. It speaks to an expected characteristic (having a pouch) and concludes that lacking this characteristic means being outside the defined category (not an opossum). This aligns with the original argument about persistence of traits ruling out normalcy.

Key concepts

Argument Structure

In logical reasoning, understanding the argument structure is crucial, especially when preparing for exams like the LSAT. The argument structure refers to the underlying framework that supports a particular argument.
In the original exercise, the argument is structured around the concept of trait persistence and category classification.
Key points of this argument structure include:

• Identifying a normal condition, such as instinctive reflexes disappearing by a certain age in full-term babies.
• Observing whether this condition persists beyond the expected time frame.
• Drawing a conclusion about belonging to a category based on this observation.

The step-by-step breakdown involves analyzing whether the given conditions logically lead to the conclusion that a subject is not a part of the normal category if the traits persist past the usual cut-off point.

Logical Reasoning

Logical reasoning is the ability to analyze arguments and assertions in a clear, objective manner.
When tackling LSAT Logical Reasoning questions, it's important to evaluate how premises lead to a conclusion. In this problem, the logical reasoning involves recognizing that the persistence of certain traits beyond the typical time frame contradicts the expected norms.
This is a signature of evaluating conditions and implications logically. Some helpful approaches include:

• Identifying premises and conclusions to see how they relate.
• Checking if the assumption holds true in all cases.
• Watching for similar patterns or deviations in other arguments.

These skills allow you to dissect the argument properly and find the most logically similar argument from the options presented.

Deductive Reasoning

Deductive reasoning is about drawing specific conclusions from general principles or premises.
In the context of the exercise, you are required to use deductive reasoning to determine if a subject fits into a category. Here's how to approach it:

• Start with a general rule, like reflexes disappearing by a set age for normal babies.
• Check if the individual case meets the conditions of this rule.
• If not, deduce that the case does not fit the general rule.

The exercise uses deductive reasoning to conclude that a baby with persistent reflexes isn’t typical because it doesn’t align with the general rule for normal babies.
Understanding this type of reasoning can enhance decision-making in logical problems.

Standardized Test Preparation

Preparing for standardized tests, like the LSAT, involves mastering various test components, including logical reasoning.
Familiarity with argument types and structures can make a significant difference. Key preparation strategies include:

• Practice with sample questions to become comfortable with different logical structures.
• Develop a systematic approach to analyzing arguments, identifying premises, and drawing conclusions.
• Learn to recognize common logical fallacies and assumptions that could mislead conclusions.

By focusing on these areas, students can improve their test performance.
It’s beneficial to review argument structures and formats regularly to build confidence in answering such questions.