Why did Voldemort want the Philosopher's Stone?
From what little I know about alchemy, one must have a pure soul in order to be able to use a philosopher's stone, which Voldemort obviously did not have. Thus, I don't understand why he wanted the stone. I feel like he should have known that it wouldn't work for him, given how brilliant and well-versed in magic he supposedly was. Has anyone ever figured out a good explanation for this? Or is this just another instance of Rowling making her characters conveniently stupid in order for the plot to work?