how to make a valid and sound argument?
- formal(deductive)
propositional fallacies——affirming a disjunct(选言命题)
一个人要成功就一定有才能或者有社会关系->小明成功了->小明有才能,小明没有社会关系
——affirming the consequent
考试作弊就可以通过考试->小明通过考试了->小明考试作弊
——denying the antecedent
如果你作弊就能通过考试->你没作弊->你不能通过考试
illicit affirmative
all movie stars are rich->some rich people are mean->therefore, some movie stars are not mean.
illicit negative
no birds are dogs->no dogs can fly->therefore, all birds can fly.
illicit major
all movie stars are rich people->no beggars are movie stars->therefore, no rich people are beggars
illicit minor
all movie stars are famous people->all movie stars are rich people->therefore, all rich people are famous people
undistributed middle
all movie stars are rich people->all ceos are rich people->therefore.all movie stars are ceos
four terms
nothing is better than true love->money is better than nothing->therefore, money is better than true love.