A city's government has decided to impose a fee

Question

A city's government has decided to impose a fee on single-use plastic bags at retail stores, arguing that this will significantly reduce plastic waste. A similar policy implemented in another city led to a 40% reduction in plastic bag usage within a year. Officials claim that since consumer behavior is similar across cities, their city should expect a comparable reduction in plastic waste.

Which of the following must be assumed for the argument to be logically valid?

(A) The fee imposed on plastic bags will be high enough to deter most consumers from purchasing them.
(B) Retail stores in the city will comply fully with the policy and not find ways to distribute plastic bags without charging the mandated fee.
(C) The availability of alternative packaging materials, such as paper or reusable bags, will not lead to an increase in overall waste production.
(D) Consumers in the city are not already using fewer plastic bags than those in the city where the policy was previously implemented.
(E) Factors other than the plastic bag fee, such as public awareness campaigns or environmental policies, did not cause the reduction in the other city.

KarishmaB · Accepted Answer

The question is tricky though fair. One could have fixated on (B), then moved on to (D) to finally settle on (E). Once you read (E), you know it is definitely (E). (A) The fee imposed on plastic bags will be high enough to deter most consumers from purchasing them. We don't need "most" (which means more than 50%) consumers to be deterred. The other city saw a 40% reduction. We are expecting a similar reduction. So less than "most" is fine. (B) Retail stores in the city will comply fully with the policy and not find ways to distribute plastic bags without charging the mandated fee. The problem here is the word "fully". We don't need them to comply fully. We need them to comply to a large extent. (C) The availability of alternative packaging materials, such as paper or reusable bags, will not lead to an increase in overall waste production. We are talking about "comparable reduction in plastic waste". Other waste is beyond our scope. (D) Consumers in the city are not already using fewer plastic bags than those in the city where the policy was previously implemented. Trap answer - even if the consumers are already using fewer plastic bags than the other city, it doesn't mean the usage cannot further decrease. It is possible, say, that the fee causes a reduction in the use of plastic bags. We are looking for around 40% reduction from its current value - whatever the current value may be. (E) Factors other than the plastic bag fee, such as public awareness campaigns or environmental policies, did not cause the reduction in the other city. Correct. What if the fee had no role to play in the decrease in usage in the other city? We are basing our plan on what happened in the other city, but what if awareness campaigns led to the reduction? We are assuming that the fee was responsible for reduction and not something else. Hence answer is (E) Answer (E) Discussion on Assumption Questions: https://youtu.be/O0ROJfljRLU

Sai_Challa · Answer

I was juggling between D & E where, the one talks about baselining of how much reduction is needed, and the other talks about the actual reason leading to reduction in plastic waste. Hence, E is more essential for the argument to hold true.

Prakriti_sharma · Answer

Assumption is an unstated belief or premise that is taken for granted as true in order to support an argument or conclusion

For this, You have to try to negate each and every option.

option E says no other factor than the plastic bag fee was the reason behind the change this means that if there were any other reasons then the whole decision of the govt would've been ill informed and won't be same as the ones in another city hence the claim in the para won't stand. so if we negate this option saying that there were other factors including public awareness campaigns then the paragraph would be wrong, making this the assumption.

egmat · Answer

The Argument's Logic: 
 
 Evidence: City X implemented a plastic bag fee →  40\%  reduction 
 Premise: Consumer behavior is similar across cities 
 Conclusion: Our city should expect a comparable reduction

Applying Negation to Each Choice:

(A) The fee will NOT be high enough to deter most consumers 
Does this destroy the argument? Not necessarily. The argument references a "similar policy" to the one that worked. The fee level is implied to be similar. This doesn't destroy the core logic.  Not necessary.

(B) Retail stores will NOT comply fully and will find ways to distribute bags without charging 
Does this destroy the argument? This seems damaging, but the argument compares to another city where the policy was implemented. We assume similar implementation conditions. While compliance matters, it's not the  fundamental  assumption the argument rests on.  Not the credited answer.

(C) Alternative materials WILL lead to an increase in overall waste 
Does this destroy the argument? No. The conclusion is about " plastic waste " specifically, not overall waste. Even if total waste increases, plastic waste could still decrease by  40\% .  Not necessary.

(D) Consumers ARE already using fewer plastic bags than those in the other city 
Does this destroy the argument? This seems problematic – if they're already using fewer bags, maybe they can't achieve the same reduction. However, "comparable reduction" could mean a similar  percentage  reduction from their current level. The argument already states "consumer behavior is similar," which addresses baseline similarity.  Not the core assumption.

(E) Other factors DID cause the reduction (not the fee itself) 
Does this destroy the argument?  YES, completely!  If the fee wasn't the cause of the  40\%  reduction in City X – if it was actually due to awareness campaigns, other environmental policies, or unrelated factors – then implementing just the fee in the new city won't produce the same results. The entire argument collapses because the causal link is broken.

Answer: (E)

Why This Feels Tricky:

Options (B) and (D) are  strengtheners  – they make the argument better but aren't strictly necessary for the logic to hold. The argument already implies similar implementation ("similar policy") and similar starting conditions ("similar consumer behavior").

Option (E) is different: it addresses  causation , which is the foundation of the argument. The argument uses City X's experience to predict City Y's outcome. This only works if the fee  caused  the reduction in City X.

Key Distinction:  Necessary assumptions are the  minimum required  for the argument to work. Strengtheners make it more convincing but aren't essential to the basic logic.

I hope this is clear enough now.

Anandanwar · Answer

Hello,
A query here.
The argument states: "A similar policy implemented in another city LED TO A 40% REDUCTION in plastic waste"

So the cause of the 40% reduction in plastic waste in another city was the policy. This is a truth according to the argument.

So choice E is a straight reject according to this analysis.

Could someone point to the logical error in above analysis?
Regards,
Ankti

guddo · Answer

I’d say the error is treating “led to” as meaning  the fee alone caused the full 40% reduction .

The statement can still be true if the fee was part of the cause, but the actual reduction also depended on other factors, such as public awareness campaigns or other environmental rules.

For this city to expect a similar result, the argument must assume that the other city’s drop was due to the  bag-fee policy itself , not mainly to some outside factor. That is exactly what (E) tests.

egmat · Answer

Hi Anandanwar,

You've spotted exactly the phrase the whole question hinges on, so let's look at it closely.

You're reading  "a similar policy... led to a 40% reduction"  as a locked-in fact that the  fee  caused the drop. That feels airtight, but here's the slip:  "led to" is just a report of what happened  after  the policy - it's a sequence/correlation, not a guarantee that the fee, and only the fee, produced the drop.

Notice two things in the exact wording:

- It credits  "a similar policy"  - a policy can be a  bundle  (fee  plus  awareness campaigns, other environmental rules). The stimulus never says the fee, isolated from everything else, did the work.
- The city here plans to impose  only the fee . So the argument quietly needs the other city's drop to be caused by  the fee itself , not by things that happened to run alongside it.

That's why  (E) is not already stated  - it's the unstated bridge. Treating "led to" as proof that the fee was the cause is the classic  correlation-as-cause  move, and  (E)  is what plugs that gap.

The negation test confirms it:  if factors  other  than the fee (say, an awareness campaign) actually drove the  40%  in the other city, then copying just the fee gives no reason to expect the same result - and the argument falls apart. An assumption you can negate to destroy the argument is a  necessary  assumption.

Turn one knob to feel it:

"A new gym opened downtown, and that year the town's obesity rate fell 40%. So opening a gym in our town will cut obesity 40% too."

Did the gym cause it, or did a citywide health campaign run the same year? "Fell  40% " doesn't tell you - and that missing causal link is precisely what  (E)  supplies here.

Answer: E

A city's government has decided to impose a fee

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A city's government has decided to impose a fee

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