There are many well known and lesser known logical fallacies. I propose a fallacy called the assumptive contradiction.
In general epistemology, a claim cannot be true and false at the same time. Such a logical system is called a consistent system. Because of this, an argument can easily be rejected if you can point out a logical contradiction based on the claims made.
This can be dangerous however because it could lead to the fallacy fallacy or an endless attempt to seek out a possible contradiction by asking the other party question after question, in the hope that you will find an answer that contradicts the argument.
Assumptive Contradiction is as follows:
Person 1 is claiming Y and uses argument P to support Y.
Person 2 points out that P implies Z and asks person 1 if Z is true.
Person 1 claims that Z is false.
Assuming that P does imply Z, there is a logical contradiction.
This can be used to reject Y. However, claiming that Y is false would be an example of the fallacy fallacy. This is because there may be some argument P2 which implies Y and which doesn’t imply Z, or because Z may actually be true.
Mary claims that the first amendment can be limited. She references the Supreme Court case in which the example of “yelling fire in a crowded building” was used. John points out that that specific case concluded that it was constitutional for congress to pass a law banning war protests and asks Mary if that’s true. Mary claims that it is unconstitutional to ban war protests.
Case 1: John rejects Mary’s argument, pointing out that if her argument were correct, then bans of war protests would indeed be constitutional. This is valid.
Case 2: John demands that, since Mary claimed that such bans are unconstitutional, the first amendment cannot be limited. This is a fallacy since it hasn’t been shown that such bans are indeed unconstitutional or that the supreme court case in question is the only possible argument for the claim that the first amendment can be limited.