Superman vs. Batman
Premise 1: Superman is stronger than Batman.
Premise 2: Batman is smarter than Superman.
Premise 3: Superman has a high level of moral integrity, and would never start a fight with a weaker opponent, especially a fellow superhero, unprovoked.
Premise 4 (Corollary to Premise 3): If Batman and Superman fought, it would be because Batman initiated the fight.
Premise 5: Batman would never initiate a fight he could not win.
Therefore, if Batman and Superman fight, it will be because Batman provoked the fight, and therefore knew that he could win. Ergo, if Batman and Superman fight, Batman will always win.