But I'm not sure that this statement, however famous it may be, captures the essential truth about the relationship. Or at least, that it captures all that is essential about the truth of how power and corruption are connected.
In saying that power tends to corrupt, Lord Acton appears to be saying that if one adds power to a person's pre-existing character, that character gets changed for the worse. This is how people almost always use Acton's famous dictim, and I think it is only a limited part of the picture.
Another part of the picture is suggested by the statement from the author David Brin:
It is said that power corrupts, but actually it's more true that power attracts the corruptible."
According to this view, if we see a great deal of corruption in the arena of power --and regrettably we surely do-- it is because the kinds of people who choose to participate in power's games are a non-random and morally sub-par group.
This view has a good deal of truth to it, methinks. Power is indeed an arena in which a zero-sum game is enacted, and it therefore attracts a disproportionate number of those who want more than their fair share.
It would be comforting to think that the extent of corruption one sees in the sphere of power were solely a reflection of this process of selection and self-selection that brings the corrupt forward to fill powerful positions. If prison guards tend toward the sadistic, one might conclude, it is because the role of prison guard is likely to be sought by people who wish to fill a role in which their sadism can express itself.
These "guards" were not an especially "corruptible" group who, because of their tendencies, were attracted to that powerful role.
I'm inclined to regard power less as a transformer of people's character, as Acton asserts, than as source of opportunity: the possession of power permits people to make manifest a part of their nature that previously was hidden. Not that power corrupts. Rather, power gives people a chance to express impulses that others --those who are weak, and thus subject to the will of others, and those who act among equals who require them to stay within certain boundaries-- keep a lid on.
This is a darker view than Lord Acton's. And darker also than Brin's. For it declares that there is corruption already embedded in the character of a great many people, and that giving such people the wider scope of action that comes with power simply serves as an invitation to put forth into the world the darkness that is already there.
And then, as people are also shaped by the actions they have taken, Lord Acton's dictim comes in again: having enacted their worst impulses, people are also transformed into something more corrupt than they had been. Were those Stanford students undiminished by what they had done? Were Hitler's Willing Executioners not degraded by their crimes? Power, by enabling corrupt actions, does corrupt.
Note, however, that I am NOT maintaining that such corruption is universal. Not ALL the prison guards in the Stanford experiment became sadistic. And not ALL the people who gain power in our world use it for corrupt purposes. Some rulers have used their power justly, for the good, without abuse, without corrupt and self-serving intent.
Imagine a person in a position of power who has reliable access to divine guidance. And suppose that the nature of this divine guidance is reliably moral in a consequentialist sense of the word. In other words, the guidance tells this powerful person which action among those available will do the most to make the world a better place. And imagine, finally, that this person invariably follows that moral/consequentialist counsel.
This thoroughly uncorrupted person in power, I am asserting, will often be guided to choose a course of action that involves him in corruption. [Note: as I speak of "he" and "him" I wish those pronouns to be understood as also including "she" and "her."]