A philosopher, a mathematician, a chemist and a physicist were at coffee shop.
The physicist turns to the chemist sitting next to him and says "You know, chemistry is just applied physics!"
They all laugh a bit at the chemist.
The mathematician turns to the physicist sitting next to him and says "You know, physics is just applied mathematics!"
They all share a laugh at the physicist.
At which point, the philosopher interjects, "And mathematics is just applied philosophy!"
The laughter roars even louder.
The mathematician turns to the philosopher and says: "That's funny. Now shut up and bring me the coffee I ordered."