自相谬误
1.Premise:The truth about human knowledge lies in the position of skepticism.
premise:There is no way that we can know anything to be true.
Conclusion:We can give up the search to explore new knowledge.
Reason: The first premise means that we should recognize the knowledge to be true or false,but in the second premise,we have no way to find the result, so these two premises contradicts with each other.
2.Premise:Each individual needs to be determine what is right and wrong.
Sub-premise: My words about using marijuana is not wrong.
Conclusion: Your words about using marijuana is wrong.
Reason: Given that each individual needs to be determine what is right and wrong, in A’s opinion it is right to use marijuana, but from B’s perspective,on the contrary,it is wrong.Nevertheless,each person has the right to decide whether it is true or not. So the conclusion is in contradiction with the premise.
否认前因：
Premise: None of our better teachers are tenured.
Premise:Our tenured faculty members are all very politically conservative.
Conclusion: None of out better teachers are politically conservative.
Reason: All politically conservative teachers are not tenured faculty members, which means that there are still a group of people who are not tenured,among which they may be better teachers.
