"It's obvious. There are so many differences between tobacco and Facebook," Bob said.
"You are wrong. They are similar, as they both shorten one's life," Alice countered.
"On the one hand, you are right. But there's a material difference. Tobacco shortens one's life by shortening its end, i.e. life's worst part. Facebook shortens one's life by shortening its middle, i.e. life's best part. That is why it's easier to give up on Facebook," Bob said.