how to make a valid and sound argument?

1. 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.

false premises

inductive：归纳 ·strong or weak的结论

1、ambiguity

2、relevance

3、逻辑跳跃

deductive：演绎~形式~valid or invalid

前题错了得出错误的结论，但reasoning没问题

（valid-unsound）

1）命题缪误：

compound propositions：相当于复合句

1、选言

2、肯定后件谬误：涉及必要、充分两个概念，前题条件是否结论的充分必要条件

3、否定前项

2）3段论

1、非法/无效肯定：正正不能得－

2、非法否定：负负不能得＋

3、大项不当周延：大项，小项，中项，周延

4、小项不当周延：在结论里变周延了

5、中项不周延：在大小前提里都不周延

6、4项错误：缺中项或不是词项逻辑，而是谓词逻辑（谓语动词不是be动词）