"...and therefore exposure to water causes the carbon to explode."
"But will it really? How can we know?"
"Well, if you'll remember the scientific method—"
"No, I mean, how can we say that one thing causes another?"
"We can discuss metaphysics some other time, but now—"
"But why talk about cause and effect when we can't even be sure it exists?"
"Interrupting like this will get you sent to the principal's office."
"... But will it really?"
"...leading to Napoleon's defeat at Waterloo."
"But how do we know this?"
"Well, there are plenty of first hand accounts, as well as—"
"No, I mean, how can we be sure that Napoleon even existed?"
"We've never seen him, and even if we did, we'd need to consider the possibility that he's an illusion."
"Fascinating, but completely irrelevant to the discussion."
"Well, I guess I have to question the relevance of a lecture about a battle we can't really know ever happened."
"If you keep interrupting, I'm sending you to the principal's office."
"... But how can we be sure the principal exists?"
"For warm-ups I want one lap around the football field."
"But that's impossible."
"Well, if I run one lap, first I'd have to run half a lap."
"So, before I run half a lap, I'd have to run half that. And before I run a quarter lap, I'd have to run half that. Before I can run any distance, I'd have to run half that distance first."
"Look, either you run the lap or I send you to the principal's office."
"...But to get to the principal's office, first I'd have to go half the distance to the principal's office..."