Logical Reasoning

PT9 · S4 · Q10 Myrna: People should follow diets

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Myrna: People should follow diets in which fat represents no more than 30 percent of total calories, not the 37 percent the average diet in this country contains.

Conclusion

Modifying our diet is not worthwhile.

Evidence

Over an entire lifetime, only 0.2 percent of people who follow Myrna’s diet advice would lengthen their lives at all, and even then, only by about three months.

A “lifetime of sacrifice” eating an unappealing low-fat diet is too high a price to pay for a mere chance of three extra months.

Evaluate

Roland’s argument is claiming that a benefit of decreasing our fat intake —slightly longer average lifespan for a very small group—isn’t worth the sacrifice.

But is that the only benefit? What if we have healthier skin? More sex drive? Fewer illnesses?

He also seems to assume that switching to a lower fat intake necessarily entail switching to an "unappealing" low-fat diet. But what if there are very pleasant ways to lower our fat intake?

Goal

Let's find an answer ruling out other benefits (besides longer life expectancy) of lowering our fat intake, or an answer attesting to Roland's assumption that lowering our fat intake would involve an unappealing low-fat diet.

10.

Roland’s argument assumes that

it is desirable to live
Opposite
Roland actually says the opposite: it is not worth striving to extend life when the payoff is small. He is not assuming that it is always desirable to lengthen life “as much as possible.”
5% picked this
Correct
a low-fat diet cannot readily
Why this is right
This has the lovable Defender "not". If we negate it, does the answer weaken? Sure! If we say that a low-fat diet can readily (i.e. "easily") be made appealing and satisfying, then where is the sacrifice? Roland’s discussion of a “lifetime of sacrifice eating an unappealing low-fat diet” shows he’s assuming that eating less fat must inevitably be unappealing. If, on the contrary, one could make that diet appealing, his argument that the tradeoff is too high would no longer hold.
Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.
77% picked this
diet is the only relevant
Too Strong: the only
Just because diet is the only factor influencing length of life that's mentioned doesn't mean the author is assuming that diet is the only factor that influences length of life. This answer would be better if it said he assumes that "Life expectancy is the only relevant factor to consider in deciding whether to modify our diet"
10% picked this
the difference in tastiness between
Opposite
Roland’s argument depends on there being a big difference (a “sacrifice”) in taste and appeal. This choice says the difference is “not noticeable,” which would undercut Roland’s “too big of a price to pay” angle.
6% picked this
not everyone in the country
Irrelevant
Whether not everyone literally eats the “average diet” does not affect Roland’s argument that adopting the low-fat approach yields too little benefit. Roland’s claim involves the hypothetical scenario in which everyone adopts Myrna’s 30% recommendation.
2% picked this

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