Description: Requiring the truth of the something that you are simultaneously trying to disprove.
Reason and logic are not always reliable, so we should not count on it to help us find truth.
Explanation: Here we are using reason to disprove the validity of reason, which is unreasonable -- reasonably speaking.
Science cannot be trusted. It is a big conspiracy to cover up the truth of the Bible and the creation story. Besides, I saw fossils in the creation museum with humans and dinosaurs together, which proves science is wrong!
Explanation: Geology is a branch of science. Using science (examining fossils through the science of geology) to disprove science is absurd, a contradiction and, therefore, a fallacy in reasoning.
Exception: Intentional irony.