1.Incompatible Premise
Premise: The truth about human knowledge lies in the position of skepticism.
Premise: From the position of skepticism, there is no way that we can know anything to be true.
Conclusion: We may as well give up the search.
Implied Premise: Truth is found on the basis of search.
Attack: The first premise is a truth whereas the second indicates that nothing can be true, which is contradictory.
2.Contradiction Between Premise And Conclusion
Premise: Each individual needs to determine what is right, including smoking marijuana.
Premise: Nothing is unethical about using marijuana.
Conclusion: One who thinks Smoking marijuana is wrong.
Implied Premise: There is only absolute right or wrong on the issue.
Attack: The first premise remarks that it is up to an individual to decide what is right and wrong. However, the conclusion states that the other, who biases against the drug, is wrong, which means that it is the arguer who helps the opponent to judge instead of the opponent himself, which is self-defeating, of course.
