Reformer: A survey of police departments keeps track of the national crime rate, which is the annual number of crimes per 100,000 people. The survey shows no significant reduction in the crime rate in the past 20 years, but the percentage of the population in prison has increased substantially, and public expenditure on prisons has grown at an alarming rate. This demonstrates that putting more people in prison cannot help to reduce crime.
A flaw in the reformer's argument is that it
infers without justification that because the national crime rate has increased, the number of crimes reported by each police department has increased
The reform points out that the national crime rate has increased based on a survey of police departments. But she never assumes that the number of crimes reported by each individual police department has also increased.
ignores the possibility that the crime rate would have significantly increased if it had not been for the greater rate of imprisonment
The reformer ignores the possibility that the crime rate might have been even higher if fewer people were imprisoned. In other words, maybe imprisoning more people actually helped keep the crime rate stable.
overlooks the possibility that the population has increased significantly over the past 20 years
It doesn't matter whether the population increased significantly because the reformer’s argument addresses the rate of crimes and the percentage of the population in prison. The number of people that makes up the population is irrelevant.
presumes, without providing warrant, that alternative measures for reducing crime would be more effective than imprisonment
The reformer’s argument only addresses the effectiveness of imprisonment on reducing crime. She doesn’t suggest any alternative measure for reducing crime, nor does she assume that other measures would be more effective. She just concludes that imprisonment is not effective.
takes for granted that the number of prisoners must be proportional to the number of crimes committed
The reformer never assumes that the number of prisoners and the number of crimes must be proportional. In fact, she doesn’t cite the actual number of prisoners or crimes at all.