Its a classic common resource problem:
http://en.wikipedia.org/wiki/Tragedy_of_the_commons"... individuals, acting independently and rationally according to each one's self-interest, behave contrary to the whole group's long-term best interests by depleting some common resource."
Historically, only 2 viable solutions exist:
1) An authority to regulate (% in this case)
2) Privatization
http://en.wikipedia.org/wiki/Tragedy_of_the_commons#Modern_solutionsPick your poison..... but be quick about it.
Ref: "The Tragedy of the Commons". Science 162 (3859): 12431248. 1968. doi:10.1126/science.162.3859.1243
Presumably you are referring to miners and their supposed free will. If so, you hit the nail on the head. Anyway...
Don't worry about it. Most people are way to fuckin stupid to understand what this means. A fair fraction of those who do understand it are in favor of having ways for the authorities to manage the solution so the 51% is a good thing. It's pretty artificial and easily rectified from a PR point of view anyway. Just give have Google with %33, Facebook with 33%, and Microsoft with 33%. The net effect is the same (or better actually) than a '51%'. Most people who welcome the control will be delighted and most people who fear it will be put at ease. The leftover dead-enders can work on something else.