The greater good fallacy is a way people try to argue a point of action that it is best for the collective for the individual to conform. This logical fallacy is common in both political and personal conversations. The Greater Good Fallacy is related to the topic of altruism.
The reason why the greater good is a logical fallacy is that there is no way to quantify that something is best for the collective, and even more so it is not possible to know what is best for everyone.
"For the greater good" or "For the many, not the few" and similar phrases is the most common tool used by leaders for evil.