Logical Reasoning

PT134 · S1 · Q9 If a child is to develop healthy

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If a child is to develop healthy bones, the child's diet must include sufficient calcium.

Conclusion

The diets of children who don't develop healthy bones must not include enough calcium.

Evidence

If a child is to develop healthy bones, the diet must include enough calcium.

Evaluation

We have one conditional premise: healthy → diet has HB → SC bones sufficient calcium

And we have a conditional conclusion that performs an illegal opposite move.

not healthy → diet not have ~HB → ~SC bones sufficient calcium

Conversationally, the flaw is that healthy bones may require more than one thing. Perhaps healthy bones require sufficient calcium as well as sufficient exercise. Thus, seeing a kid without healthy bones doesn't immediately mean they don't get sufficient calcium. Maybe they get plenty of calcium but not sufficient exercise.

Goal

So, we're looking for an argument that presents a conditional premise, "if A, then B", and then gives us an illegal opposite conclusion that says, "things that aren't A apparently aren't B"

9.

Flawed reasoning in which one of the following most closely parallels the flawed reasoning in the argument above?

  1. If bread is to have

    Valid Logic

    This presents a conditional premise, firm crust ? baked right temp And then presents a valid contrapositive conclusion, ~baked right temp ? ~firm crust

    14% picked this

  2. Correct

    A cake must contain the

    Why this is right

    This presents a conditional premise, taste good ? right amount of flour and then concludes an illegal opposite conclusion, ~taste good ? ~ right amount of flour

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

    77% picked this

  3. The Bake-a-Thon, which is open

    Different Flaw (past = future)

    This presents a conditional premise, although one that is not a timeless rule but rather a historically true universal: won contest ? was 30+ yrs old Then it illegally assumes that "past patterns will continue to apply in the future" in order to conclude this year's winner = 30+ yrs old

    8% picked this

  4. Both yeast and baking powder

    Bad Premise Match

    The premise isn't a conditional (unless you willfully force it to be). And the conclusion certainly isn't an illegal opposite. An illegal opposite conclusion would sound like, "Thus, if an ingredient isn't yeast or baking powder, then it can't cause sweet rolls to rise".

    1% picked this

  5. In recipe contests, there are

    Different Flaw (assumes equal chance)

    This barely has something we could consider a conditional premise. It is a historically true universal: recipe contest ? (historically) pies > cakes We could already bail from this, but if we continued, we'd need the conclusion to give us an illegal opposite, such as, "Thus, if a content isn't about recipes, then there will be more cakes than pies".

    1% picked this

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