As Twitter has far too few characters to make a compelling argument against PRP I have decided to blog the reasoning, so here goes:
Education is a non zero-sum game (which basically means if somebody else becomes better, nobody else loses out because of this) so it is in everybody's interests for new ideas to propagate quickly, because 'beating' the competition serves no purpose as the victory doesn't really reward you in any substantial way.
Hedge Funds (Dominic Cumming's example) is a zero-sum game (this basically means a success for me means a failure for somebody else) so it is in the interests of the 'best' companies to keep their secrets. Anything that confers a competitive advantage should not be shared as it is what makes the company the 'best'.
At the moment education is basically treated as a non-zero sum game because being better (and in education it is usually an idea as opposed to a product and ideas can propagate very easily) doesn't lead to anything extra that is really substantial.
When you start paying for performance then you change education from being a non-zero sum game to more of a zero sum game - because anything that gives you a competitive advantage now has a tangible value. This now means the paradigm shifts to a much slower propagation of ideas, as it is in the interests of teachers not to share as once the idea becomes common knowledge, the competitive edge is gone.
I wanted to show there is a precedent here - and there is. Another non-zero sum game is health (just because I get healthier doesn't mean somebody else becomes less healthy) so it is in everybody's interest for a quick spread of ideas so everybody wins. However, if health becomes a zero sum game, as in if a person comes to my practice, more money for me, less for you, then it is in the interests of people with a competitive edge to keep that edge, to not help other people.
So I draw my argument to a close with the story of forceps in hospitals - ostensibly 'invented' in 1734 to help with difficult births, however Dr Peter Chamberlen had invented it before 1670. So for more than 150 years a way to reduce infant mortality was kept quiet due to health being treated as a zero-sum game.
The Forceps Family
'Peter the Elder is believed to be the inventor of the forceps. The
brothers went to great length to keep the secret. When they arrived at
the home of a woman in labour, two people had to carry a massive box
with gilded carvings into the house. The pregnant patient was
blindfolded so as not to reveal the secret, all the others had to leave
the room. Then the operator went to work. The people outside heard
screams, bells, and other strange noises until the cry of the baby
indicated another successful delivery.
The secret was kept in the family for another three generations.'