The legislator concludes that lawmakers should approve the act. As support, he says that his colleague has previously voted for laws that deter investment, so this must not be her real reason for opposing the act. Since she hasn't explained her real reason, the legislator argues, it must not be persuasive.

The legislator’s argument is most vulnerable to criticism because he attacks his colleague’s motivation for making an argument rather than attacking the argument itself. This is the cookie-cutter “ad hominem” flaw.
He rejects his colleague’s recommendation only because she supported similar acts before, so he assumes that her “real reason” for opposing the act isn’t persuasive. He doesn’t address his colleague’s argument that the act will deter investment, nor does he provide any reason to believe that lawmakers should approve the act.

A new computer system will only really increase an organization’s efficiency if the new system forces employees into more productive work habits. The Ministry of Transportation is getting a new system that accommodates its employees’ existing work habits. So, what can we conclude?
In Lawgic:
P1: new system improves efficiency → requires more productive work habits
P2: Ministry’s new system → /requires change in work habits
C: ?

Based on these facts, we can conclude that the Ministry’s new system does not force employees into more productive work habits. We can further conclude that it will not meaningfully increase the Ministry’s efficiency.

The columnist concludes that car manufacturers likely inflate fuel efficiency numbers. He supports this by saying that, despite manufacturers highlighting their cars' fuel economy under normal driving conditions, he has never gotten close to the advertised fuel economy of any of the three cars that he's owned.

This is the cookie-cutter flaw of using too small of a sample. The columnist draws a conclusion about the fuel economy claims of all manufacturers based on his experience with only three cars. But there are dozens of car manufacturers and thousands of car models on the market. Driving three cars isn’t a reliable way to test the fuel economy of every kind of car. Maybe most manufacturers’ claims are accurate and the columnist just purchased three bad cars.

The columnist also assumes that his driving conditions are “normal.”

The author concludes that if more landlords install individual electricity meters on tenant dwellings (thereby giving individuals an incentive save energy), energy will be conserved. This is because tenants who don’t have to pay for their own electricity bills don’t have a financial incentive to conserve electricity.

The author assumes that the financial incentive created by the indvidual electricity meters is powerful enough to cause people to actually change their behavior. The author also assumes that there aren’t other aspects of using individual electricity meters that would cause more energy use that could outweigh whatever savings are created by the individual’s own incentive to use less energy.

The position that criminals should be punished in proportion to the severity of their crimes but that repeat offenders should receive harsher sentences is flawed. It wrongly assumes that past misdeeds are relevant to the seriousness of an offense. This introduces a vague standard that would make almost every other consideration relevant, making it impossible to apply this proportional principle.

This is a undesirable consequence of believing the argument that the author is refuting.

For any government practice that might facilitate abuse of power:
If there’s no compelling reason to do the practice → don’t do it
Keeping government secrets is a practice that might facilitate abuse of power.
Concealing the keeping of a government secret is another kind of practice that might facilitate abuse of power.

If there’s no compelling reason to keep a government secret, the government should not keep the secret.
If there’s no compelling reason to conceal the fact that the government is keeping a secret, the government should not conceal the fact they are keeping a secret.
Note that keeping a secret and concealing the keeping of a secret are two different actions.

Heavy tapestry fabrics are only for applications that do not need frequent laundering. These applications do not include any types of clothing, but include types of window treatments such as swags and balloon valances.

If a fabric is appropriate for clothing, then that fabric is not a heavy tapestry fabric.

Increased housing supply generally leads to lower rents for existing apartments, but rents for existing apartments in Brewsterville rose when the housing supply increased.

The correct answer will be a hypothesis that explains why, contrary to what usually happens, existing apartments became more expensive when the housing supply increased. This explanation must show some quirk in Brewsterville’s housing situation that causes rents to rise with supply, or else some other factor that affected the prices of existing apartments without factoring in housing supply.