The return of organic wastes to the soil is a good solution to waste disposal problems only if the wastes are nontoxi...

amandapaige on February 24, 2019


Why is answer choice D wrong? I identified the pattern as don't just reverse but found both B and C had the same flaw.

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Ravi on February 26, 2019


Happy to help. Let's take a look at the stimulus before we dive into
the answer choices.

The first sentence gives us a conditional statement:

Return of organic waste good solution - >wastes are nontoxic and not
too much energy expended

We're then told that with small-scale organic farming, the wastes are
nontoxic, and not too much energy is expended

Small-scale organic farming - >wastes are nontoxic and not too much
energy expended

From this, the argument concludes that returning wastes to the soil is
a good solution for small-scale organic farms.

This argument is saying

A - >B and C

B and C

Therefore, A

This argument is calling on the necessary condition to invoke the
sufficient condition, and this is false logic. Confusing the
sufficient and necessary conditions is a very common LSAT flaw.

The question asks, "Which one of the following exhibits flawed
reasoning most similar to the flawed reasoning exhibited by the
argument above?"

We know what the flaw is, so let's look at the answer choices.

You had said you thought (B) and (C) had the same flaw and wanted to
know why (D) is wrong, so let's look at these.

(B) says, "When every country has equal access to markets, which will
be the case 20 years from now, globalization of markets will provide a
way for each country to optimize its use of resources. So,
globalization of markets will show the desired results 20 years from

The issue with (B) is that it doesn't have the type of conditional
logic problems we found in the stimulus.

(B) is basically saying

A - >B


Therefore B'

The conclusion in (B) doesn't quite match the premise, which is why I
put B' instead of B for the conclusion. That said, (B) is not making
the same mistake of satisfying the necessary condition and concluding
the sufficient condition as is found in the stimulus, so we can get
rid of this choice.

(C) says, "To be viable, a business idea must be clear, cost-
effective, practical, and responsive to a market demand. Your idea for
a website information service has all these properties, so it is

(C) is basically saying

Viable - >C + CE + P + R

C + CE + P + R

Therefore, Viable

This argument is satisfying the necessary conditions and trying to
conclude the sufficient condition. This is exactly the type of flaw we
found in the stimulus, so this is the correct answer choice.

(D) says, "Those competitors—and only those—who meet all of the
following criteria are eligible for the award: they must be under 19
years of age, be in secondary school, and have played the sport for at
least the two years immediately preceding the competition. You meet
all the criteria, so you are eligible."

(D) is tricky, but it's not quite the flaw we see in the stimulus.
"Those...and only those" in the first sentence of (D) means that the
first relationship described is a biconditional one.

Competitor that meets criteria< - >eligible for the award

(You) meet criteria

Therefore, you're eligible for the award

This is a valid argument, as based on the premise we're given, the
criteria are both necessary and sufficient. This isn't the same flaw
as we found in the stimulus, as it isn't calling on the necessary
condition to invoke the sufficient condition. We can get rid of this

Does this make sense? Let us know if you have any more questions!