The following argument could be strengthened: "Generally, Toyotas are very reliable cars. Tony drives a Toyota. Therefore, Tony probably drives a reliable car". Strengthening the argument can be accomplished in a variety of ways. Perhaps the simplest way to strengthen the argument is to modify the qualifiers in the second and third sentences as shown here: "All Toyotas are reliable. Tony drives a Toyota. Therefore, Tony drives a reliable car". The original argument could also be revised in this way: "Generally, Toyotas are very reliable cars. Tony drives a Toyota and his car is as reliable or more reliable than the average Toyota. Therefore, Tony probably drives a reliable car".
The original statement is missing critical information that could weaken or discount the conclusion that Tony probably drives a reliable car. In the original argument we must infer the condition of a single event from statistics on the entire population of Toyotas. The original argument does not provide any data about the repair history and reliability of Tony's Toyota. If Tony's car had proven to be unreliable based on the number of times that it had been in for repair, we would certainly not conclude that his car was reliable.
Additionally, the model and year of Toyota is not mentioned in the statement. The quality of Toyota cars will vary my model and year. For example, it is likely that Toyota's top of the line cars like the Avalon are more reliable than the less expensive models and that newer Avalons are more reliable than older models. The omission of specific information constitutes large flaws in the logic of the original argument. Without clarification, the original hypothesis is weak.
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