Logical Reasoning

PT148 · S1 · Q13 If the purpose of laws

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If the purpose of laws is to contribute to people's happiness, we have a basis for criticizing existing laws as well as proposing new laws.

Main Conclusion (we must conclude)

Existing laws acquire legitimacy simply because they are laws.

Intermediate Conclusion (Hence)

If the purpose of laws is not to contribute to people's happiness, then we have no basis for the evaluation of existing laws.

Evidence

If the purpose of laws is to contribute to people's happiness, then have a basis for criticizing existing laws as well as proposing new laws.

Evaluate

Since the argument draws two conclusions, we can examine both moves. The move from the 1st claim to the 2nd claim commits the #1 famous flaw Necessary vs. Sufficient, in which the author introduces a conditional statement and then interprets it using illegal backwards or negated logic.

The first sentence says purpose is happiness → we have a basis The conclusion drawn from that is just an illegal negation. purpose is not happiness → do not have basis

The move from the 2nd claim to the 3rd claim is saying, .

We might be able to fight that by saying, or ?

Goal

It seems more likely that we're just being tested on the age old Necessary vs. Sufficient flaw and that the bonus conclusion was put in there just as a way to distract us and "hide the ball".

Whenever we're doing Flaw and see any conditional logic, we should immediately start suspecting an illegal reversal or illegal negation (aka, Necessary vs. Sufficient)

13.

The reasoning in the argument is flawed in that the argument

  1. Correct

    takes a sufficient condition for

    Why this is right

    As we anticipated, this is just calling out the illegal negation the author performed in going from claim 1 to claim 2. "having the purpose of contributing to happiness" is identified in the first sentence as a condition that would sufficiently guarantee that we have a basis for evaluating laws. In the 2nd sentence, the author acts like if we don't have that condition, we can't have any basis. So she starts acting as though that condition is necessary for having a basis for evaluating laws.

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

    78% picked this

  2. infers a causal relationship from

    Not Causal

    This speaks to the 2nd most common Famous Flaw, Causal Overconfidence, in which an author overconfidently assumes / concludes one possible causal interpretation of the evidence, even though other possibilities exist. That didn't happen here. We could say that the final conclusion infers a causal relationship between "Being a law" and "acquiring legitimacy", but there wasn't a premise that said "Being a law and acquiring legitimacy are correlated".

    4% picked this

  3. trades on the use of

    Not Equivocation

    This describes one of the other top 10 Famous Flaw, Equivocation, in which an author uses the same term twice in an argument but to mean very different things. This, like Circular and Self-Contradiction, is almost never a correct answer. There were no terms in this argument used in different ways.

    5% picked this

  4. draws a conclusion about how

    Bad Evidence Match

    Did the author draw any conclusion about how the would actually is? Sure, we could say the final conclusion about "existing laws get their legitimacy from being laws" is about the world that actually is. Was there a premise talking about what should be the case? Not at all.

    10% picked this

  5. infers that because a set

    Not Whole to Part

    This describes one of the other top 10 famous flaws, Part vs. Whole, in which an author assumes that a trait that is true of each part of a whole must therefore be true of the collective itself, or vice versa. There is no part vs. whole aspect to this argument.

    3% picked this

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