I think this has been statistically proven[1]. So I should probably add that in addition to a well crafted constitution that prevents any single party from enacting a damaging law, such a constitution needs to be revised or rewritten whenever a single party has been deemed to gain such power.
Revising and rewriting the constitution needs to be done with the utmost care off course and have ample democratic safeguards to prevent a dictator.
A true democracy has the power to revise its constitution when that constitution is no longer able to protect the democracy it defines from a dictator.
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1. Almost 10 years ago I learned D3 by building an interactive graph testing this in a game of capitalism. After a few rounds of completely fair zero-sum trades where all parties start with the same amount, the bulk of the wealth will always accumulate on few hands.
Imagine an almost perfectly balanced democracy where everyone has nearly equal agency and power. At some point, maybe at the political level of brownian motion, someone will have a tiny edge. They will naturally use that bit of extra power to garner a little more power. Because the most useful thing to with a little extra power is always to capture some more.
Compound that over many iterations and your democracy is dead.
Thus, I believe that all systems of equality and democracy need active, constant recalibration to maintain fairness. There is no perfectly written constitution that you can set in motion like clockwork and have it run flawlessly forever. There is no static equilibrium, but you can have dynamic equilibrium. Constant vigilance.