What Is Exclusion Principle?

There are three distinct Exclusion Principles. One of Economics, one of philosophy and one of Quantum mechanics called 'Pauli exclusion principle'.

The philosophical exclusion principle is a debate on mental and physical events which do or do not supercede each other. Does the mind always control the movement of ones foot? Etc.   
Pauli Exclusion Principle which is very important in Quantum physics goes to explain properties of atoms and specifically electrons. It states that the same space cannot be occupied by any two electrons in a closed system in other words the same Quantum state. It was put forward by Wolfgang Pauli in 1925.    

The economic exclusion principle is to do with suppliers of commodities and their ability to withhold service unless provided recompense. In God we trust but everybody else pays cash.