Yes, you do! Mathematical proofs are just common-sense reasoning with a higher standard of precision. For example, suppose you have two magnets. You put an end of the first magnet to an end of the second one, and they repel. You have to prove that either both ends that you put together are north or both are south. Well, how could it be otherwise? If one were north and the other south, then ...I just don't understand proofs at all..