1.(1) incompatible premises
(2)Premise1：The truth about human knowledge lies in the position of skepticism.
Premise2: The skepticism is that there is no way that we can know anything to be true.
The second premise that there is no way that we can know anything to be true means that we also can’t know either if the first premise is true, that human knowledge lies in the position of skepticism. So no acceptable can be drawn.
2.
(1)contradiction between premise and conclusion
(2) Premise1: Each individual needs to determine what is right.
Premise2: I don’t see anything unethical about using marijuana.
Conclusion：You are just wrong.
The conclusion is incompatible with the premise 1. If each individual needs to determine what is right, the defender also should determine if using marijuana is right.
