Conclusions and roles

Some city council members argue that residents have lost interest in the downtown library branch, pointing to a fall in its visitor numbers last year. But the fall coincided with eight months of construction that blocked the branch's main entrance. In the four months after the entrance reopened, visitor numbers were higher than in the same months of the year before. So last year's fall in visitor numbers is not good evidence that residents have lost interest in the branch.

Historian: Many people believe that the printing press quickly ended the copying of books by hand. But records from monasteries show that hand copying of religious texts continued for nearly a century after printed editions became available. Since monks had little reason to copy texts that could be bought more cheaply, this suggests that printed editions were not, at first, cheaper than hand copies.

Mayor: Opponents of the new bike lanes say the lanes have increased traffic congestion on Elm Street. But if that were so, average driving times on Elm Street would have risen since the lanes opened. City sensors show that average driving times there have not changed. So the opponents' claim is false.

Critic: The museum's new wing is being praised for its energy efficiency. Yet building it required demolishing a sound older building, and the energy used to construct the new wing exceeds what its efficiency will save over the next forty years. So the wing will not reduce energy use for decades. Therefore, the praise the wing has received for its environmental benefits is premature.

Economist: Raising the minimum order for free delivery will reduce the number of small orders the store receives. Small orders account for most of the store's delivery losses. Hence, the change will reduce delivery losses. And because those losses are the main reason the store is unprofitable, the change should improve the store's profitability.

Omar: Students should not be allowed to use calculators in introductory math courses, because students who rely on calculators never learn to do arithmetic in their heads.

Lena: By that reasoning, students should not be allowed to use dictionaries in writing courses, since students who rely on dictionaries never learn to spell. Yet nobody thinks dictionaries should be banned.

Although tomato plants grown in greenhouses produce more fruit per plant than those grown outdoors, greenhouse growing is not the better choice for most small farms in our region. Greenhouses are expensive to heat during our long springs, and the extra fruit rarely sells for enough to cover that cost. Moreover, small farms here earn much of their income from customers who will pay more for field-grown produce.

Some nutrition writers claim that eating late at night causes weight gain. But in a controlled study, people who ate the same meals at different times of day gained the same amount of weight. What matters for weight, then, is how much people eat, not when. The common belief probably persists because people who eat late often also eat more.