轻率概括.ppt

Hasty Generalization (Converse Accident)
轻率概括
Hasty generalization
Hasty generalization is a fallacy that affects inductive generalizations. The fallacy occurs when there is a reasonable likelihood that the sample is not representative of the group.
Such a likelihood may arise if the sample is either too small or not randomly selected.

归纳概括轻率概括
样本很有可能不具有代表性
样本数量太小样本不是随机选取
Example⑴
After only one year the alternator went out in 'Grady's new Chevrolet. Mrs. Dod-son's Oldsmobile developed a transmission problem after six months. The obvious conclusion is that cars made by General Motors are just a pile of junk these days.
In the argument a conclusion about a whole group is drawn from premises that mention only a few instances. Because such small, atypical samples are not sufficient to sup-port a general conclusion, each mits a hasty generalization.
typical drawing
Hasty
generalization
Generalization
Specfic case(s)
(not representative)
General rule
Attention Ⅰ
The mere fact that a sample is small, however, does not necessarily mean that it is atypical. On the other hand, the mere fact that a sample is large does not guarantee that it is typical. In the case of small samples, various factors may intervene that render such a sample typical of the larger group.
Examples⑵
Ten milligrams of substance Z was fed to four mice, and within two minutes all four went into shock and died. Probably substance Z, in this amount, is fatal to mice in general.
In the second argument the fact that the mice died in only two minutes suggests the existence of a causal connection between eating substance Z and death. If there is such a connection, it would hold for other mice as well.
Examples⑶
On three separate occasions I drank a bottle of Figowitz beer and found it flat and bitter. Probably I would find every bottle of Figowitz beer flat and bitter.
In the third example the fact that the taste of beer typically remains constant from bottle to bottle causes the