An astronomer, a physicist and a mathematician are an a train in Scotland.
The astronomer looks out the window and sees a black sheep standing in a field and remarks, "How odd, all sheep in Scotland are black!".
"No no no!" Says the physicist, "only some sheep in Scotland are black".
The mathematician rolls his eyes at his companions' muddled thinking and says, "In Scotland, there is at least one sheep, at least one side of which appears to be black from here some of the time"


Nice start, but if you remember the history of philosophy lecture we just had (on Tuesday), we can get a lot more skeptical than that mathematician.