Justice is a moral virtue, merely because it has that tendency to the good of mankind, and indeed is nothing but an artificial invention to that purpose. The same may be said of allegiance, of the laws of nations, of modesty, and of good manners. All these are mere human contrivances for the interest of society.
David HumeWe have no other notion of cause and effect, but that of certain objects, which have always conjoin'd together, and which in all past instances have been found inseparable. We cannot penetrate into the reason of the conjunction. We only observe the thing itself, and always find that from the constant conjunction the objects acquire an union in the imagination.
David HumeWe learn the influence of our will from experience alone. And experience only teaches us, how one event constantly follows another; without instructing us in the secret connexion, which binds them together, and renders them inseparable.
David Hume