Logical ReasoningDifficulty: Hard

PT114 S1 Q9 Explanation

Some scientists believe that 65

A free, expert breakdown of this official LSAT Logical Reasoning question.

TopicsParadox

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Stimulus

Some scientists believe that 65 million years ago an asteroid struck what is now the Yucatán Peninsula, thereby causing extinction of the dinosaurs. These scientists have established that such a strike could have hurled enough debris into the atmosphere to block sunlight and cool the atmosphere. Without adequate sunlight, food sources for ground within six months, too soon for the plants to disappear or the dinosaurs to freeze.

What this question is testing

Paradox

Your task

Break the argument into its conclusion and evidence, then do exactly what the question stem asks with that structure.

Common trap

Answers that sound relevant to the topic but don't connect to the argument's actual reasoning.

Winning move

Predict what a right answer must do, then test each choice against the conclusion-evidence gap.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
9.

Which one of the following, if true, most helps to resolve the apparent discrepancy between the scientists’ beliefs and the scientists’

Answer choices

  1. No Impact4% picked this

    Loss of the herbivorous dinosaurs would have deprived the carnivorous dinosaurs of

    This answer would be perfect if the paradox we were resolving was, "Given that the asteroid would only have killed off the herbivorous dinosaurs food source, how did it make all the dinosaurs go extinct"? This answer would be saying "asteroid leads to blocked sun, which leads to dead plants, which leads to dead herbivorous dinosaurs, which leads to dead carnivorous dinosaurs". The problem is we were told that the debris would only hang in the air for six months, which is too little time for the plants to disappear. So since we have no reason to think the plants disappear in the aftermath of this asteroid, we don't have reason to think the herbivorous dinosaurs die-off because their food source has disappeared. Thus, this answer doesn't get triggered, because it only has impact if we know that the herbivorous ones have died off.

  2. Deepens the Paradox5% picked this

    Dinosaurs inhabited most landmasses on the planet but were not especially abundant in the area

    One possible way to explain how the asteroid could cause the dinosaurs' extinction would be if all the dinosaurs in the world were gathered locally for some dinosaur Burning Man in the Yucatan. They would die from the impact itself, not from the ecological chain reactions. (There actually is another LSAT question that tells this exact story to resolve a similar dinosaur asteroid extinction paradox) But this answer says the opposite. It's saying "most dinosaurs would not have been killed by the initial strike", so we're even more confused how they went extinct, given that the secondary threat only lasted six months.

  3. No Impact7% picked this

    A cloud of debris capable of diminishing sunlight by 20 percent would have cooled the earth’s surface by

    These are just specific facts about debris and temperature, but we don't know by percent the Yucatan asteroid dimmed the sun, so we can't apply the information in this answer to the paragraph.

  4. Too Weak18% picked this

    The asteroid was at least 9.6 km in diameter, large enough for many dinosaurs to be killed by the strike itself

    Large enough for "many" dinosaurs to be killed ain't good enough. We know lots of local dinosaurs will get killed in the immediate blowback from the impact, but to render them extinct on a global scale, we need to kill more than just "many" of them.

  5. Correct67% picked this

    Dinosaurs were susceptible to fatal respiratory problems caused by contamination of the air

    Why this is right

    This gives us a possible way to explain how debris that didn't last long enough to freeze the dinosaurs or kill off the plants that herbivorous ones ate could still have been deadly enough to cause an extinction. If all the dinosaurs got lung cancer during those six months, that could be enough to kill them off on a global scale. Remember that Paradox answers don't have to be bulletproof; they just have to create a storyline by which we could potentially resolve the paradox.

    Skill tested: Paradox · how this choice captures the argument's function is the move to repeat next time.

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