"the sun came up today."
"yeah."
"and it’s going to come up tomorrow."
"yeah??"
"well duh!"
"how do you know?"
"because I know."
"how?"
"because that’s what the sun does! it rises."
"but how do you know that it will rise tomorrow?"
"what kind of question is that? of course it will rise tomorrow. it rose today, and it rose yesterday, and every single day before that since the beginning of time. so of course it’s going to rise tomorrow."
"what makes you think that just because the sun has risen every day in the past, it’s going to rise tomorrow? you are saying that just because something has happened in the past, that’s enough reason to believe that it will happen in the future? why? maybe the sun won’t rise tomorrow. you have no reason to believe that it will."
"but do you realize what that means? our whole life depends on assumptions we have about what will happen in the future based on the past. according to you there is NO REASON AT ALL to believe that things will happen tomorrow the way they did today. So basically what you’re saying is that there is no reason for believing ANYTHING. I don’t even have a reason to believe that my finger will type another letter just because it has typed all these letters already."
"that’s exactly what I’m saying."
"ok, I’m scared...will the sun rise tomorrow?"
"(pause) sure it will, don’t worry...go back to sleep"