Since the mayor's publicity campaign for Greenville's bus service began six months ago, morning automobile traffic into the midtown area of the city has decreased seven percent. During the same period, there has been an equivalent rise in the number of persons riding buses into the midtown area. Obviously, the mayor's publicity campaign has convinced many people to leave their cars at home and ride the bus to work.

Which of the following, if true, casts the most serious doubt on the conclusion drawn above?

(A) Fares for all bus routes in Greenville have risen an average of five percent during the past six months.
(B) The mayor of Greenville rides the bus to City Hall in the city's midtown area.
(C) Road reconstruction has greatly reduced the number of lanes available to commuters in major streets leading to the midtown area during the past six months.
(D) The number of buses entering the midtown area of Greenville during the morning hours is exactly the same now as it was one year ago.
(E) Surveys show that longtime bus riders are no more satisfied with the Greenville bus service than they were before the mayor's publicity campaign began

This is a classic causality argument. The argument says, in essence, that the mayor's campaign for the bus service is what caused the decrease in automobile traffic and an increase in the number of people riding buses. As an arrow diagram

mayor campaign ---> auto traffic decrease/bus riders increase

If we want to weaken this argument, we'd need to show that it was not, in fact, the mayor's campaign that led to this outcome, but rather, something else. C gives us an alternative cause. It could be the case that: road construction ---> auto traffic decrease/bus riders increase

You argue that E is either irrelevant or a mild strengthener. We know that more people are riding buses. We're just trying to understand why. Is it because the mayor has convinced them to, or some other reason? Unchanged satisfaction levels don't really shed any light on this question. (And logically, one wouldn't necessarily expect satisfaction levels among bus riders to change if the mayor's campaign were the root cause of the increase in riders. Of course, if the root cause were some kind of dramatic upgrade in bus quality, that would cause satisfaction levels to rise, but now we can be reassured that there has been no such upgrade, so one potential alternative explanation has been eliminated from consideration.)

Hi Dave,
Need some help to CORRECTLY understand the very reasons to eliminate Option E.

The phrase bus riders are no more satisfied than they were before means that (Case 1) EITHER bus riders are AS SATISFIED AS they were before
(Case 2) OR bus riders are LESS SATISFIED than they were before. Right ?

For Case 1, it seems that it's a mild strengthener in this situation. OR it might be simply an irrelevant consideration.

For Case 2, it might be a strengthener in that if we construe that in spite of this fact more people travel in bus than in car (MOST LIKELY because of mayor's publicity campaign) or a weakener as well in that it seems to DIRECTLY attack the LOGIC in the premise that why more people would travel in bus than in car by contradicting the PREMISE in some way (and it seems to indicate a FLAW in the argument).

Thus, option E is a weird option to conclude!

Please let me know your thoughts!

RBBmba@2014 wrote:Hi Dave,
Need some help to CORRECTLY understand the very reasons to eliminate Option E.

The phrase bus riders are no more satisfied than they were before means that (Case 1) EITHER bus riders are AS SATISFIED AS they were before
(Case 2) OR bus riders are LESS SATISFIED than they were before. Right ?

For Case 1, it seems that it's a mild strengthener in this situation. OR it might be simply an irrelevant consideration.

For Case 2, it might be a strengthener in that if we construe that in spite of this fact more people travel in bus than in car (MOST LIKELY because of mayor's publicity campaign) or a weakener as well in that it seems to DIRECTLY attack the LOGIC in the premise that why more people would travel in bus than in car by contradicting the PREMISE in some way (and it seems to indicate a FLAW in the argument).

Thus, option E is a weird option to conclude!

Please let me know your thoughts!

I'd argue that E is just irrelevant. Look closely at the language. "Surveys show that longtime bus riders are no more satisfied." The mayor's campaign started six months ago. Why would longtime bus riders be more satisfied now than they were before the campaign? (And why would a publicity campaign have any impact on satisfaction levels? If the bus is delayed and you're late for work, would a billboard with the mayor's smiling face do anything to mitigate your unhappiness? And you're right that the riders could be less satisfied now- perhaps they're unhappy because the buses are more crowded. But even if this is the case, it sheds no light on whether the buses are more crowded because of the mayor's publicity campaign or some other reason.)