Logical Reasoning

PT123 · S2 · Q14 A cup of raw milk after being heated

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A cup of raw milk, after being heated in a microwave oven to 50 degrees Celsius, contains half its initial concentration of a particular enzyme, lysozyme.

Conclusion (therefore)

What destroys the enzyme is not heat itself but heat obtained via microwaves.

Evidence

If you heat milk via microwave to 50 degrees Celsius, it contains half its initial concentration of a particular enzyme, lysozyme.

But if you heat milk via conventional heat source to 50 degrees Celsius, it still has basically all its lysozyme.

Evaluate

This is an Anti-Causal conclusion and a Causal conclusion. It's saying .

With causal / anti-causal conclusions, we typically can use our Explain Curious Fact framework.

Curious Fact: how come the lysozyme gets cut in half when you microwave milk to 50º?

Author's Explanation: it's the microwaves themselves ruining the lysozyme, not the heat.

Goal

Given this framework, we weaken by suggesting an Alternate Explanation for the curious fact:

Or by hurting the plausibility of the Author's Explanation:

If we were just doing our standard Weaken prephrase, we'd think in terms of the Anti-Conclusion:

14.

Which one of the following, if true, most seriously weakens the argument?

  1. Heating raw milk in a

    Unclear Impact

    The destruction of the enzyme could be explained by either the temperature or the microwaves. If anything, this just seems to reinforce that heating via microwave is bad for the enzyme, which would strengthen the author's conclusion.

    5% picked this

  2. Enzymes in raw milk that

    Out of Scope

    Whether destroyed enzymes can be replaced is not relevant to the argument. We're here to figure out the causal mystery of why 50º microwaved milk has so much less lysozyme than does 50º conventionally heated milk. This answer joins the story after the murder of the lysozyme's has already been committed and asks, "Who will take Lyso's place, now that it's gone?" We're trying to figure out what killed Lyso in the first place.

    7% picked this

  3. A liquid exposed to a

    Irrelevant Comparison

    The rate at which a liquid reaches 50 degrees Celsius is not relevant to this argument. This is just telling you that the liquid on your stovetop will heat up more quickly if you turn up the burner (i.e. hotter conventional heat sources accelerate the warming process).

    24% picked this

  4. Milk that has been heated

    Irrelevant Comparison

    The taste of milk is not relevant to this argument. We're only concerned with the mystery of the missing lysozyme.

    3% picked this

  5. Correct

    Heating any liquid by microwave

    Why this is right

    This weakens the argument by supporting the possibility that heat is what explains the discrepancy in the concentration of the enzyme. It could be the zones that are much hotter that destroy the enzyme. It gives us an Alternate Explanation for why more lysozyme is destroyed via microwaving: it's not that microwaves themselves are to blame. It's just that temperatures higher than 50º are to blame. The microwave is creating certain zone that might be 80º while others are only 20º. The liquid will average out to be 50º, but those 80º areas were so hot that they destroyed the lysozyme in them. Meanwhile, we assume, conventional ovens don't work this way, and so they manage to heat something to 50º without causing specific zones in there to be much hotter than 50º. This answer helps us argue the Anti-Conclusion, that what destroys the lysozyme IS the heat.

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

    61% picked this

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