Logical Reasoning

PT105 · S1 · Q9 All potatoes naturally contain solanine

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All potatoes naturally contain solanine, which is poisonous in large quantities.

Conclusion

Peeling wild potatoes makes them at least as safe to eat as unpeeled domesticated potatoes of the same size.

Evidence

All potatoes (wild and domestic) have solanine, which is poisonous in large quantities.

Wild potatoes contain poisonous levels of solanine, while domesticated potatoes contain only very small amounts of solanine.

Most of the solanine in potatoes is concentrated in the skin.

Evaluate

We need to prove that peeled wild potatoes are at least as safe to eat as unpeeled domesticated potatoes.

Did the argument ever define some proving mechanism, like ?

No, so the correct answer would need to do that.

When it comes to wild potatoes' dangerous levels of solanine, most of the solanine is found in the skin, so if you've peeled a wild potato, then you've eliminated most of its solanine.

But is the residual amount of solanine in the peeled wild potato still less safe to eat than the small amount of solanine that's in domesticated potatoes?

If domesticated potatoes only have 10g of solanine, whereas wild potatoes have 100g of solanine, peeling a wild potato would mean that there is at most 49g of solanine left, but that could still be more solanine than what's in a domesticated potato, and that could still be a high enough level of solanine to be "dangerous".

Furthermore, who says that "solanine level" is the only metric by which we should be judging whether wild potatoes are at least as safe to eat as domesticated potatoes?

Maybe there are other differences between the two that make wild potatoes less safe to eat.

Goal

The correct answer needs rule out all possible ways that wild potatoes could still be more dangerous to eat (even peeled, their residual solanine is too high / there's some other dangerous ingredient they have that domesticated potatoes lack).

Or it needs to provide us with a rule that we know applies to peeled wild potatoes and outputs language like "at least as safe".

9.

Which one of the following, if assumed, allows the conclusion above to be properly drawn?

  1. The proportion of a potato's

    Too Weak

    This probably strengthens somewhat, because it's making it sound even more like a wild potato keeps most of its solanine in its skin. But even still, there is some solanine left in the peeled wild potato. Is it at least as safe to eat as a domesticated potato? Are there any other ingredients in a wild potato that make it less safe to eat? Since this answer doesn't rule out those concerns, it doesn't prove the conclusion is true beyond any doubt.

    15% picked this

  2. The amount of solanine concentrated

    No Impact

    We already know that a wild potato is poisonous and that it keeps most of its solanine in its skin. This answer is telling us that amount in the skin by itself is enough to be poisonous. Do we care? No, we care about what solanine is left in the peeled wild potato. Is the amount of solanine found in the non-skin part of a wild potato large enough by itself to be poisonous? Are there any other ingredients in a wild potato that make it less safe to eat? Since this answer doesn't rule out those concerns, it doesn't prove the conclusion is true beyond any doubt.

    8% picked this

  3. Correct

    There is no more solanine

    Why this is right

    This answer is surprising, because it only proves that wild potatoes are at least as safe when it comes to solanine. It doesn't actually address the loose end that there could be other ingredients in a wild potato that make it less safe. That's pretty frustrating on LSAT's part, either as a sloppy oversight or as an intentional betrayal of what this question stem is supposedly asking us for. We talked earlier through this possible type of objection: suppose domesticated only have 10g of solanine, whereas wild have 100g of solanine. If so, then peeling a wild potato (i.e. removing its skin, where most of the solanine is) would mean that there is at most 49g of solanine left, but that could still be more solanine than what's in a domesticated potato. This answer squashes that line of objection. We can't say that what's left in the peeled wild potato is still more than what's in the unpeeled domesticated potato. This answer says that when it comes to solanine, peeled wild potato is at least as low as unpeeled domesticated So it "proves" the conclusion that when it comes to being safe to eat, peeled wild potato is at least as safe as unpeeled domesticated

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

    73% picked this

  4. There are no poisonous substances

    Weakens (if anything)

    This rules out the idea that domesticated potatoes have something else unsafe in them. It leaves open the possibility that wild potatoes have something else unsafe in them. So, if anything, this takes us farther away from proving that peeled wild potatoes are at least as safe as domesticated potatoes.

    3% picked this

  5. Wild potatoes are generally much

    No Impact

    The conclusion is about comparing wild / domesticated potatoes of the same size, so the natural variation in sizes is irrelevant to assessing this conclusion.

    0% picked this

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