Hard LSAT Complete the Argument Questions Practice Questions

Concept Explanation

LSAT Complete the Argument questions, often identified by a blank line at the end of a stimulus, require you to select the choice that most logically finishes the author's train of thought. These questions are essentially a variation of Must Be True or Main Conclusion tasks, where the correct answer must be supported by the premises provided. Success on hard LSAT Complete the Argument questions depends on your ability to track the scope of the argument and identify the specific logical direction established by transition words like "therefore," "since," or "however." Unlike standard reading comprehension, these questions demand a rigorous adherence to the internal logic of the passage without introducing outside information.

To solve these efficiently, you must distinguish between two types of completions. The first type asks for a conclusion that follows from the premises. The second type asks for a premise that completes an explanation or resolves a paradox mentioned in the text. According to the Law School Admission Council (LSAC), logical reasoning involves identifying the relationships between statements. When you encounter a blank, treat it as a structural hole that can only be filled by a piece of information that shares the same "logical DNA" as the preceding sentences. You can find more structured guidance on general test-taking through the LSAT Prep hub.

Solved Examples

Below are three examples of how to approach complex completion prompts by analyzing structural cues and logical flow.

1. Example 1: The Logical Extension
   Stimulus: Many economists argue that increasing the minimum wage leads to higher unemployment because businesses cannot afford the extra labor costs. However, recent data shows that in regions where the minimum wage was raised, consumer spending increased significantly, leading to higher revenues for local businesses. Therefore, the claim that raising the minimum wage necessarily increases unemployment ______.
   Solution:
   1. Identify the contrast: The word "However" introduces evidence that contradicts the economists' initial claim.
   2. Analyze the evidence: Consumer spending and business revenue went up.
   3. Complete the thought: Since business revenue increased, the premise that they "cannot afford labor" is weakened. The blank should say the claim is "unsupported" or "overlooks compensatory factors."
   4. Final Answer: ...is based on a premise that does not account for the stimulative effect of increased consumer spending.
2. Example 2: Filling the Gap in a Comparison
   Stimulus: Technique A is more efficient than Technique B for extracting minerals, but it requires a significantly higher initial investment. If a mining company prioritizes long-term profitability over immediate liquidity, and if the cost of the investment is recovered within five years, then for such a company ______.
   Solution:
   1. Identify the conditions: (1) Long-term profit > short-term cash, (2) Investment pays back in 5 years.
   2. Connect to the techniques: Technique A is more efficient (long-term gain) but costs more (short-term hit).
   3. Draw the conclusion: Under these conditions, the company should choose the more efficient method.
   4. Final Answer: ...Technique A is the preferable choice despite its higher upfront cost.
3. Example 3: Resolving a Causal Paradox
   Stimulus: The city expected the new highway bypass to reduce traffic congestion in the downtown core. However, six months after the bypass opened, downtown traffic volume remained unchanged, even though thousands of cars were using the bypass daily. This suggests that the bypass ______.
   Solution:
   1. Identify the paradox: Bypass is used, but downtown traffic didn't drop.
   2. Consider the cause: If cars are using the bypass but the city is still full, those "new" cars must be replacing the ones that left, or the bypass is attracting new drivers who previously avoided the area.
   3. Complete the thought: The bypass likely induced new demand rather than just diverting existing traffic.
   4. Final Answer: ...attracted new drivers to the area who would not have traveled through the city otherwise.

Practice Questions

Test your skills with these hard LSAT Complete the Argument questions. Focus on the logical bridge between the last premise and the blank.

1. Scientists have observed that deep-sea hydrothermal vents support unique ecosystems by releasing minerals that bacteria convert into energy. Because these ecosystems do not rely on sunlight, they are often cited as models for life on frozen moons like Europa. However, the high pressure and extreme heat of these vents are conditions that most known terrestrial life forms cannot survive. Thus, if we use these vents to predict the possibility of life on other planets, we must assume that ______.

2. A recent study found that employees who take short breaks every hour are more productive than those who work four hours straight. Management consultants argue that companies should mandate these breaks to maximize output. Yet, the study also showed that the productivity boost only occurred when the breaks were voluntary and used for relaxation. Therefore, mandating breaks ______.

3. Art critics often argue that a painting's value is determined solely by its aesthetic qualities. However, when a famous painting is revealed to be a forgery, its market value plummets even if its aesthetic qualities remain identical to what they were before the discovery. This phenomenon indicates that ______.

4. Legal analysts note that the new privacy law will likely decrease the amount of data tech companies can collect. While this protects consumer privacy, it also limits the ability of these companies to provide personalized advertisements, which is their primary source of revenue. If these companies cannot find an alternative revenue stream, then the new law ______.

5. Historians traditionally believed that the collapse of the ancient civilization was caused by a sudden volcanic eruption. However, recent soil samples show that a prolonged drought began fifty years before the eruption occurred, leading to a gradual decline in crop yields. Since the civilization was already significantly weakened by the time the volcano erupted, it is likely that ______.

6. Most bird species that migrate long distances rely on magnetic fields for navigation. A new study shows that certain types of electronic interference can disrupt a bird's ability to sense these fields. If this interference becomes widespread along major migratory routes, it is reasonable to conclude that ______.

7. Philanthropists argue that direct cash transfers to the poor are more effective than donating goods because they allow recipients to prioritize their own needs. Critics, however, claim that recipients often spend the cash on non-essential luxury items. If data shows that 95% of cash transfers are spent on food, education, and healthcare, then the critics' objection ______.

8. Software developers often use open-source code to speed up the creation of new programs. While this practice is efficient, it also means that a single vulnerability in a popular open-source library can be propagated across thousands of different applications. Consequently, the widespread use of open-source code ______.

Answers & Explanations

1. Answer: ...life on those planets can thrive in conditions of extreme pressure and temperature.
   Explanation: The stimulus sets up a comparison between earth's vents and other planets. If the vents are to be used as a model, the assumption must bridge the gap between the "extreme" conditions of the vents and the potential for life elsewhere.
2. Answer: ...might not result in the same productivity gains observed in the study.
   Explanation: The study specifies that the boost is linked to the voluntary nature of the breaks. If they are mandated, the "voluntary" condition is removed, so the result (productivity) may not follow.
3. Answer: ...factors other than aesthetic qualities, such as authenticity, contribute to a painting's value.
   Explanation: Since the value drops while aesthetics stay the same, there must be another variable (authenticity) that dictates market value.
4. Answer: ...could pose a significant threat to the financial stability of those tech companies.
   Explanation: The argument links the law to a loss of primary revenue. Without an alternative, the logical result is financial hardship.
5. Answer: ...the eruption was the final blow rather than the primary cause of the civilization's demise.
   Explanation: The evidence shows the decline started long before the eruption due to drought, suggesting the eruption just finished what the drought started.
6. Answer: ...migratory birds may experience significant difficulties in reaching their destinations.
   Explanation: If migration depends on magnetic fields and those fields are disrupted by interference, the birds' ability to navigate (and thus arrive) is compromised.
7. Answer: ...is largely unsupported by the actual spending patterns of the recipients.
   Explanation: The data (95% on essentials) directly contradicts the critics' claim that cash is spent on non-essential luxuries.
8. Answer: ...increases the systemic risk of widespread security failures in the software industry.
   Explanation: The stimulus explains how one small flaw can spread to thousands of apps, which is the definition of a systemic risk.

Frequently Asked Questions

How do I identify a Complete the Argument question?

These questions are easily spotted because the stimulus ends with a blank line, often preceded by a conclusion indicator like "therefore," "thus," or "it follows that." The question stem will typically ask you to select the option that most logically completes the passage.

Are these questions more like Must Be True or Strengthen questions?

They are most similar to Must Be True questions because the correct answer must be a valid inference based strictly on the provided text. You are not looking for something that could be true, but something that must follow logically from the author's premises.

Should I look for the main conclusion in these prompts?

Yes, because the blank is often the main conclusion itself. If the stimulus provides several premises but hasn't yet made a point, your job is to identify what those premises are collectively trying to prove.

Can I use outside knowledge to fill in the blank?

Absolutely not. The LSAT is a test of formal logic, and using outside information—even if it is a well-known fact—will often lead you to a trap answer that is not supported by the specific text provided.

What should I do if two answers seem logically sound?

Compare the strength of the language and the scope. If one answer uses "all" and the other uses "some," the "some" answer is often safer and more likely to be supported by the premises, unless the premises themselves are absolute.

How can I practice these specifically?

You can use tools like an AI Question Generator to create variations of logical reasoning prompts. Focus on identifying the relationship between the "before" and "after" of transition words to predict the ending before looking at the choices.