The laws of states are uniform to about the same extent as houses, which must have a roof and walls, windows and chimneys, because the end in view demands certain essentials; but beyond these, there is every conceivable diversity.
It is true that, by education and custom, we blame injustice without thinking of its ultimate consequences.

So universal are the rules of justice, from the universality of its end, that we approve of it mechanically.

Still, we have often to recur to the final end, and to ask, What must become of the world if such practices prevail?
How could society subsist under such disorders?
Thus, then, Hume considers that, by an inductive determination, on the strict Newtonian basis, he has proved that the SOLE foundation of our regard to justice is the support and welfare of society: and since no moral excellence is more esteemed, we must have some strong disposition in favour of general usefulness.

Such a disposition must be a part of the humane virtues, as it is the SOLE source of the moral approbation of fidelity, justice, veracity, and integrity.
Section IV.

relates to POLITICAL SOCIETY, and is intended to show that Government, Allegiance, and the Laws of each State, are justified solely by Utility.
If men had _sagacity_ to perceive, and _strength of mind_ to follow out, distant and general interests, there had been no such thing as government.