7. A chemist, a physicist, and an economist are trapped on a desert island with 1 can of food but no can opener.
The physicist says "If we take a rock and throw it with a certain force and a certain angle, it will hit the can and open it so we can eat."
The chemist says "If we mix salt deposits with some of the chemicals from our signalling flare, we'll create a corrosive chemical that will eat through the metal of the can so we can eat."
The economist pauses for a moment and says "Let's start by assuming that we have a can opener."