Scott Aaronson (MIT C.S. prof) blog post on Eigenvectors and Prediction Markets

[martinBrown]

His post starts by discussing an idea of "Eigenmorality".

In an attempt to measure the players' morality, Tyler uses the eigenmorality idea from before. The extent to which player A "cooperates" with player B is simply measured by the percentage of times A cooperates. ... This then gives us a "cooperation matrix," whose (i,j) entry records the total amount of niceness that player i displayed to player j.  Diagonalizing that matrix, and taking its largest eigenvector, then gives us our morality scores.

Note that the linear algebra here, diagonalizing a matrix and taking its largest eigenvector (aka principal eigenvector), is exactly what TruthCoin does, by way of Singular Value Decomposition (SVD) on the vote-matrix. The largest eigenvector of the TruthCoin vote-matrix is the voter consensus, and that "consensus vector" is then used as the input to Reputation Based Coin Redistribution (RBCR).


After outlining Eigenmorality, his train of thought leads to linear algebra for crowdsourced democracy:

At first glance, the above definitions sound ludicrously circular—even Orwellian—but we now know that all that's needed to unravel the circularity is a principal eigenvector computation on the matrix of trust.  And the computation of such an eigenvector need be no more "Orwellian" than ... well, Google.  If enough people want it, then we have the tools today to put flesh on these definitions, to give them agency: to build a crowd-sourced deliberative democracy, one that "usually just works" in much the same way Google usually just works.

But wait, how would using linear algebra work better than relying on trusted subject-matter experts? Because, linear algebra lets us objectively distinguish liars' attempts to distort the consensus:

Now, would those with axes to grind try to subvert such a system the instant it went online?  Certainly. ... So there would arise a parallel world of trust and consensus and "expertise," mutually-reinforcing yet nearly disjoint from the world of the real.  But here's the thing: anyone would be able to see, with the click of a mouse, the extent to which this parallel world had diverged from the real one. ... The deniers and their think-tanks would be exposed to the sun; they'd lose their thin cover of legitimacy.

Here he proposes using an eigenvector as a "force of law":

But the point of an eigentrust system wouldn't be to convince everyone.  As long as I'm fantasizing, the point would be that, once people's individual decisions did give rise to a giant connected trust component, the recommendations of that component could acquire the force of law.  The formation of the giant component would be the signal that there's now enough of a consensus to warrant action, despite the continuing existence of a vocal dissenting minority—that the minority has, in effect, withdrawn itself from the main conversation and retreated into a different discourse. ... This is still democracy; it's just democracy enhanced by linear algebra.

This is what TruthCoin does. Again, the principal eigenvector of the vote-matrix becomes a "force of law" (as in the Lawrence Lessig slogan, "code is law") that awards/redistributes p2p digital coins.

The obligatory citation of Robin Hanson and futarchy:

Other people will object that, while we should use the Internet to improve the democratic process, the idea we're looking for is not eigentrust or eigenmorality but rather prediction markets.  Such markets would allow us to, as my friend Robin Hanson advocates, "vote on values but bet on beliefs."  For example, a country could vote for the conditional policy that, if business-as-usual is predicted to cause sea levels to rise at least 4 meters by the year 2200, then an aggressive emissions reduction plan will be triggered, but not otherwise.  But as for the prediction itself, that would be left to a futures market: a place where, unlike with voting, there's a serious penalty for being wrong, namely losing your shirt.  If the futures market assigned the prediction at least such-and-such a probability, then the policy tied to that prediction would become law.
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But just like Google, whatever its flaws, works well enough for you to use it dozens of times per day, so a crowd-sourced eigendemocracy might —just might— work well enough to save civilization.

An addendum in response to the comments discussion. He asks, is there a way to incentivize people and "suss out the truth"?

Moving on to eigendemocracy, here I think the biggest problem is one pointed out by commenter Rahul.  Namely, an essential aspect of how Google is able to work so well is that people have reasons for linking to webpages other than boosting those pages' Google rank.  In other words, Google takes a link structure that already exists, independently of its ranking algorithm, and that (as the economists would put it) encodes people's "revealed preferences," and exploits that structure for its own purposes.
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By contrast, consider an eigendemocracy, with a giant network encoding who trusts whom on what subject.  If the only reason why this trust network existed was to help make political decisions, then gaming the system would probably be rampant: people could simply decide first which political outcome they wanted, then choose the "experts" such that claiming to "trust" them would do the most for their favored outcome.  It follows that this system can only improve on ordinary democracy if the trust network has some other purpose, so that the participants have an actual incentive to reveal the truth about who they trust.  So, how would an eigendemocracy suss out the truth about who trusts whom on which subject?  I don't have a very good answer to this, and am open to suggestions.

A couple of comments already hint at the similarities to bitcoin:

That "trust" network discussion reminds me of the bitcoin network somehow...
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(1) This seems very similar to the block chain innovation used in bitcoin.

See also: HN discussion

[psztorc]

This is pretty awesome, and someone already left a Truthcoin comment (although the comments section has been completely overwhelmed).

When I learned about factor analysis, it did blow my mind and changed completely the way I view the world, so I can certainly relate to this. I need to reread this post carefully, but I wonder why he focuses completely on "morality" and not just "how everything gets its definition" / "is defined". Then you could define things as "desireable" or "profitable" or "uninteresting" or "red" and then work from there. That was more my interpretation of eigenknowledge.

Also, at the end there he says that prediction markets won't work for something that isn't measurable. My opinion is that of Thorndike, paraphrased: "Whatever exists at all exists in some amount. Whatever exists in some amount, that quantity can be measured."