Plaintiff’s intestate was killed when the roof of the defendant’s foundry fell in on him. Plaintiff alleges that the defendant failed to make proper repairs to the roof, and that such neglect of the defendant caused the roof to collapse. The defendant claims, however, that the roof collapsed during a violent storm, and that, even though the roof was in disrepair, the high winds caused the roof to fall. What issue is raised, and how would you resolve it?