The ‘end’: the theoretical objective of what one or many set out to achieve.
The ‘means’: the ways in which the one or many try to achieve the ‘end’.
Problem #1
There is never an end unless we’re talking about ‘The End’. ‘The End’ is the actual end of life. Humans and their pursuits cease to exist.
Problem # 2
The ‘end’ is subjective to begin with. Whose end? Yours? Everyones? An end theoretically signals some new beginning, but this is a messy transition. Most people won’t agree when this transition occurs. This incomprehension contributes to…
Problem # 3
Living systems, especially human oriented systems, have living memory. If you justify your ‘ends’ by any ‘means’, there will be collateral damage and if that collateral damage survives the ‘means’, it won’t soon forget any negative consequences they endured. It is likely that someone’s ‘end’ is the catalyst for another’s newly identified ‘end’ that are opposing in nature. In other words, group A’s objective, achieved in a way that was damaging to Group B, now causes Group B to have an objective that seems retaliatory or opposing to Group A.
What really seems to be the fundamental flaw in reasoning that the end justifies the means is that there exists no second order effects. That consequences don’t also produce more consequences, but in dynamic systems, actions have consequences and those consequences have consequences. For those who believe some end justified the means, there is a strong chance that they received benefit from the end without regard of the cost endured by others. There is also an extreme lack of appreciation for the complexity and messiness of life and the reality that your end is not meaningful at all to others.
System Tinker 