Ethics is a moral system.
From the perspective of a civilization, ethics is the last line of defense, and is often the first to be breached.
In the universe, civilizations are as numerous as stars, with various types of intelligent species, various styles of technological systems, and even unimaginable advanced civilizations.
These existences will create irresistible temptation for some intelligent species.
Often, fortresses are breached from within.
For example, a certain Carbon-Based Civilization, inspired by an Advanced Civilization, first illuminated its industrial system, leading to an explosion in productivity. Then, it lit up human body transformation technology, spurring species' mechanical evolution. Next, it developed brain modification technology, bringing about a burst of wisdom...
Ethical divergence +10%
Ethical divergence +20%
Ethical divergence +30%
Then, there was no "then".
