Things you'll find in Gothic fiction: spooky settings, mysterious characters, and all sorts of supernatural craziness.
Things you'll find in philosophical literature: deep, difficult statements about human nature.
Things you'll find in "Young Goodman Brown": all of the above.
Like his contemporaries Herman Melville and Edgar Allan Poe, Hawthorne became famous for using tried-and-true Gothic conventions in smart, philosophically rich ways. You could say he fused low culture (Gothic) with high (philosophy). It's an odd, potentially unstable mixture. Which is why it's so fascinating.