Logical ReasoningDifficulty: Medium

PT122 S4 Q20 Explanation

Magazine article: Sugar consumption may

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

TopicsNecessary Assumption

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Stimulus

Magazine article: Sugar consumption may exacerbate attention deficit disorder (ADD) in children. A recent study found that children produce large amounts of adrenaline within hours after consuming large amounts of sugar. This increase in adrenaline is especially noticeable if the source of sugar is not ameliorated by the ingestion of other foodstuffs.

What this question is testing

Necessary Assumption

The Argument

The article is about how sugar might worsen ADD. The evidence: sugar makes children produce a lot of adrenaline. The conclusion: sugar may make ADD worse.

Evaluate

Notice the gap. The evidence is about adrenaline. The conclusion is about ADD. The argument never explicitly connects adrenaline to ADD. To make this argument work, we need to assume that adrenaline can affect ADD severity.

Goal

The right answer should be the bridge between adrenaline and ADD — the unstated piece linking the evidence to the conclusion.

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

The question
20.

Which one of the following is an assumption on which the argument in the

Answer choices

  1. Bad Assumption4% picked this

    The adrenaline level of children who do not have ADD is not increased by

    The argument does not need adrenaline production in non-ADD children to be unaffected by sugar. The conclusion is about how sugar affects children with ADD. Negate this answer (sugar does affect adrenaline in non-ADD children) and the argument still works fine — it would still be the case that sugar drives adrenaline up in ADD children, and that adrenaline could exacerbate ADD. Not necessary.

  2. Too Strong5% picked this

    Overproduction of adrenaline causes ADD in

    The conclusion is that sugar may exacerbate ADD — make existing ADD worse — not that adrenaline causes ADD. These are different claims. The argument does not need adrenaline to be the cause of ADD. Negate this answer (adrenaline does not cause ADD) and the argument can still work: sugar can make existing ADD more severe via adrenaline without causing ADD in the first place.

  3. Bad Assumption1% picked this

    The most effective way to treat ADD in children is to restrict their

    The conclusion is that sugar may exacerbate ADD — not that restricting sugar is the most effective treatment. Treatment effectiveness is a separate question. Negate this answer (restricting sugar is not the most effective treatment) and the argument still holds: sugar could still exacerbate ADD without being the most important treatment factor.

  4. Correct79% picked this

    Increased adrenaline production can make ADD more severe

    Why this is right

    This is the bridge. The evidence connects sugar to adrenaline. The conclusion connects sugar to worsened ADD. The missing link is between adrenaline and ADD severity. This answer fills exactly that gap. Negate it — "increased adrenaline production cannot make ADD more severe" — and the argument falls apart, because the only thing sugar produces according to the evidence is adrenaline, and if adrenaline does not affect ADD, sugar would not affect ADD either. The argument depends on this.

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

  5. Bad Assumption10% picked this

    Sugar consumed with food substances other than candy does not substantially increase the level of adrenaline in the

    The argument needs sugar to affect adrenaline in ADD children, but it does not need to specify that non-candy sugar fails to do this. The stimulus says candy produces especially noticeable adrenaline because other foods do not ameliorate the effect — but the argument does not require sugar with food to be ineffective. Sugar with food could still produce adrenaline (just less) and the argument's chain still works. Negate this and the argument is unaffected.

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