The philosophical founder of the constitution's ideas of separation of powers was

Charles de Secondat, Baron de Montesquieu was the pioneer and author of " The Spirit of the Laws", a treatise of political theories published in 1748.

In this he presented arguments for a constitutional government and proposed three branches for that. The idea was for all of these three to have specialized powers which will have the check and balance of other branches to avoid any misuse of power.