Logical Reasoning

PT102 · S4 · Q18 Obviously, we cannot in any real

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Obviously, we cannot in any real sense mistreat plants.

Conclusion (obviously)

We cannot mistreat plants.

Evidence (and)

Plants do not have nervous systems. Having a nervous system is necessary to experience pain.

Evaluate

The premises chain together to tell us that plants cannot experience pain.

There's a New Concept in the Conclusion: mistreat.

Goal

We need to get from what we know about plants, "They can't experience pain", to what we need to prove about plants, "They can't be mistreated".

So let's look for an answer saying

or its contrapositive, .

18.

The conclusion above follows logically if which one of the following is assumed?

  1. Any organism that can experience

    Reversal / Negation

    We wanted "if can't exp pain, then can't be mistreated" and this is the illegal negation "if can exp pain, then can be mistreated" We know that plants can't experience pain, so this rule about things that can experience pain is totally irrelevant to plants and can't be used to prove something about plants.

    10% picked this

  2. Only organisms that have nervous

    Premise Support

    "Only organisms that have nervous systems can experience pain" simply restates a premise already given in the stimulus ("having a nervous system is necessary to experience pain"). You never want your answer on an Assumption question to look like it's re-wording an individual claim, and this answer is just dealing with the concepts from the 3rd claim of the stim. Correct linking answers bring together wording from two different claims.

    9% picked this

  3. Any organism that has nervous

    Reversal / Negation

    The third claim of the stimulus (i.e. the 2nd premise) says that a nervous system is required to experience pain. This answer says a nervous system is sufficient to experience pain. Well who cares? Plants don't have nervous systems, so a rule about what a nervous system guarantees you does nothing to tell us anything about plants. You never want your answer on an Assumption question to look like it's re-wording an individual claim, and this answer is just dealing with the concepts from the 3rd claim of the stim. Correct linking answers bring together wording from two different claims.

    4% picked this

  4. Correct

    Only organisms that can experience

    Why this is right

    This gives us our prediction "if you can't experience pain, can't be mistreated" ONLY introduces necessary ideas. Mistreated → Experience Pain The contrapositive is Can't experience pain → Can't be mistreated We know that plants don't have nervous systems and thus they can't experience pain. And this then tells us that they can't be mistreated, so we've proven our conclusion.

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

    70% picked this

  5. Any organism that has nervous

    Reversal / Negation

    This is a rule for things that have nervous systems. Plants do not, so this rule will tell us nothing about plants. Had it said, "anything that lacks a nervous system can't be mistreated" we'd happily pick it.

    6% picked this

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