Logical Reasoning

PT158 · S4 · Q13 Medical researcher: A new screening

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Medical researcher: A new screening test detects certain polyps at such an early stage that it is generally unclear whether the polyps are malignant.

Conclusion (Thus)

The new screening test can prompt dangerous operations that actually are not medically necessary.

Evidence

The new screening test detects some polyps that turn out not to be malignant, but doctors usually have them surgically removed, which is a dangerous process.

Evaluate

The conclusion is very weakly worded; it's only claiming that the new test can prompt a dangerous operation that is not medically necessary.

Do we know that the new test has prompted any "dangerous operations"?

Not yet, but it has the potential to, since it will detect very early polyps, which aren't clearly malignant or benign. Most doctors, not wanting to risk leaving a polyp inside someone in case it turns out to be malignant (i.e. cancerous), will surgically remove the polyp, which is a dangerous process.

So, while we don't know that the new test has already prompted any polyp removal operations, it seems pretty likely that it could. And we know those operations are dangerous because they told us so.

Do we know that the polyp removal surgery was "medically unnecessary"?

Not quite. We're getting the sense that the author thinks,

But maybe that's too big a leap. Maybe it's medically necessary to remove polyps for other reasons, whether or not they're malignant.

Goal

Look for an answer expressing the author's linking move,

or look for an answer ruling out some objection, like .

13.

Which one of the following is an assumption that the medical researcher's argument requires?

  1. A surgical operation that is

    Out of Scope

    This answer introduces a general ethical principle about when dangerous surgery is justified — namely, that it should only be performed for conditions more dangerous than the surgery itself. But the argument does not depend on any such sweeping principle. The argument's reasoning is narrower: it moves from "some polyps are nonmalignant" to "some surgeries are unnecessary." The assumption needed is a factual claim about nonmalignant polyps specifically, not a broad ethical standard governing all surgery. Apply the negation test: if we deny this principle (dangerous surgery can sometimes be justified even without a more dangerous condition), the argument about unnecessary polyp surgery still stands on its own terms.

    7% picked this

  2. Correct

    Surgical removal of nonmalignant polyps

    Why this is right

    The argument concludes that the test leads to unnecessary dangerous surgeries because some removed polyps are nonmalignant. This reasoning requires the assumption that removing nonmalignant polyps is not always medically necessary. Without this assumption, the argument collapses: if every nonmalignant polyp removal were medically justified — because nonmalignant polyps cause blockages, carry future cancer risk, or create other medical complications — then no surgery would be truly "unnecessary," and the conclusion would fail. Apply the negation test: "Removal of nonmalignant polyps IS always medically necessary." If that were true, every polyp removal prompted by the test would be justified, and the conclusion that some surgeries are unnecessary becomes impossible. The negation destroys the argument, confirming this is a necessary assumption. Note the careful wording: "not always" means "at least sometimes unnecessary" — an appropriately modest claim for a necessary assumption.

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

    66% picked this

  3. If the new screening test

    Out of Scope

    The argument concludes that the test leads to some unnecessary surgeries — a limited critique identifying a drawback. It does not conclude that the test should be abandoned entirely. A medical test can have downsides (some unnecessary procedures) while still being valuable overall (catching genuinely malignant polyps). The argument does not need the stronger assumption that the test should not be used. Apply the negation test: if we deny this (the test should continue to be used), the argument's conclusion that some surgeries are unnecessary still holds perfectly well.

    7% picked this

  4. A polyp detected by the

    Wrong Category

    This answer addresses malignant polyps — the uncontroversial side of the issue. Nobody disputes that cancerous polyps should be removed. The argument's gap concerns nonmalignant polyps and whether their removal is always necessary. Affirming that malignant polyps need surgery does nothing to bridge the gap between "nonmalignant" and "unnecessary removal." It is answering a question the argument is not asking.

    5% picked this

  5. The screening test is medically

    Too Strong

    This answer claims the test is useful "only when" it detects polyps requiring treatment. The argument does not need such a restrictive assumption about the test's overall utility. The test could be useful for many purposes — monitoring, early detection, research — while still leading to some unnecessary surgeries. The argument's narrow conclusion is about unnecessary procedures, not about the test's entire value proposition. The "only when" language creates a condition far stronger than what the argument requires. The necessary assumption is simply that some nonmalignant polyp removals are medically unjustified — not that the test has limited usefulness.

    15% picked this

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