Modelu Flashcards
Arguments that apply a generalization to a case are intended to be valid.
“False.”
Such applications are inductive, so they are not intended to be valid, and they are usually not valid. Even if 99.999999999999999% of F are G, and a is an F, it is still possible that a is not G; so an argument that concludes that a is G is not valid.
Specify what, if anything, is the main problem with the following applications of generalizations to cases. There might be more than one problem, but indicate the main one.
The weather forecast says that there is only a 40% chance of rain, so it won’t rain, and we don’t need to bring an umbrella.
“The percentage is too high.”
If there were only 10% chance of rain, then it might be reasonable not to bring an umbrella, but a 40% chance of rain is too high for confidence that it will not rain.
Specify what, if anything, is the main problem with the following applications of generalizations to cases. There might be more than one problem, but indicate the main one.
Our heater works most of the time, so we can depend on it to keep us warm during the blizzard that is coming.
“The percentage is too low.”
The word “most” means “over 50%”, but the fact that the heater works over 50% of the time is not enough to make it reasonable to depend on it when you might freeze to death in the blizzard if it fails this time.
The attribute class occurs in the conclusion when we apply a generalization to a case in an argument of the form: Almost all F are G, and a is F, so a is G.
“True.”
In this form of argument, the attribute class is G, and G does appear in the conclusion.
Specify what, if anything, is the main problem with the following applications of generalizations to cases. There might be more than one problem, but indicate the main one.
P1:Almost all Prime Ministers of Great Britain have been men.
P2: Margaret Thatcher was Prime Minister of Great Britain.
Therefore,
C: Margaret Thatcher is a man.
“The argument overlooks a conflicting reference class.”
Margaret Thatcher is also in the group of people named “Margaret”. A high percentage of people named “Margaret” are not men. Indeed, a high percentage of Prime Ministers named “Margaret” are not men. So this class—Prime Ministers named “Margaret”— is a conflicting reference class that the argument overlooks.
An argument that applies a generalization to show that a case has a certain property is never strong when the percentage in the premise is 50%.
“True.”
If 50% of F are G, then this percentage gives us no reason to believe either that a certain a that is F is G or that it is not G. Notice that an application can be strong with 50% in the premise if the conclusion is that there is a 50% chance that F is G, but then that conclusion does not claim that a case has a certain property, as the question specifies.
Specify what, if anything, is the main problem with the following applications of generalizations to cases. There might be more than one problem, but indicate the main one.
“The argument overlooks a conflicting reference class.”
Ducks are also in the group of aquatic birds. A high percentage of aquatic birds can swim. So this class—aquatic birds—is a conflicting reference class that the argument overlooks.
Arguments that apply a generalization to a case are defeasible.
True.”
Additional information can defeat the strength of such applications by showing that the individual (a) falls into a smaller reference class that is more or less likely to be G. The example in the lecture was that you might see that Walter was not wearing shoes while he was teaching.
Arguments that apply a generalization to a case commit the fallacy of overlooking a conflicting reference class when another smaller reference class that was not mentioned in the argument has a very different (higher or lower) percentage of Gs that would support a conflicting conclusion.
“True.”
The sentence in this question defines what the fallacy of overlooking a conflicting reference class is.
An argument that applies a generalization to a case is never strong when the percentage in the premise is very low.
“False.”
A very low percentage can give strong evidence for a NEGATIVE conclusion when the reference class is appropriate. Here’s an example: Only 1% of F are G, and a is F, so a is probably NOT G. (Admittedly, this question was tricky, but I hope you get the point.)
An argument from the premise that 99% of F are G to the conclusion that this F (namely, a) is G is stronger than an argument to the same conclusion from the premise that 90% of F are G.
“True.”
Increasing the percentage in the premise makes an application stronger when the conclusion is positive.
The reference class occurs in the conclusion when we apply a generalization to a case in an argument of the form: Almost all F are G, and a is F, so a is G.
“False.”
In this form of argument, the reference class is F, and F does not appear in the conclusion.
