Polymath-style attack on the Parliamentary Model for moral uncertainty

bydanieldewey4y26th Sep 201474 comments


Thanks to ESrogsStefan_Schubert, and the Effective Altruism summit for the discussion that led to this post!

This post is to test out Polymath-style collaboration on LW. The problem we've chosen to try is formalizing and analyzing Bostrom and Ord's "Parliamentary Model" for dealing with moral uncertainty.

I'll first review the Parliamentary Model, then give some of Polymath's style suggestions, and finally suggest some directions that the conversation could take.

The Parliamentary Model

The Parliamentary Model is an under-specified method of dealing with moral uncertainty, proposed in 2009 by Nick Bostrom and Toby Ord. Reposting Nick's summary from Overcoming Bias:

Suppose that you have a set of mutually exclusive moral theories, and that you assign each of these some probability. Now imagine that each of these theories gets to send some number of delegates to The Parliament. The number of delegates each theory gets to send is proportional to the probability of the theory.  Then the delegates bargain with one another for support on various issues; and the Parliament reaches a decision by the delegates voting.  What you should do is act according to the decisions of this imaginary Parliament. (Actually, we use an extra trick here: we imagine that the delegates act as if the Parliament's decision were a stochastic variable such that the probability of the Parliament taking action A is proportional to the fraction of votes for A. This has the effect of eliminating the artificial 50% threshold that otherwise gives a majority bloc absolute power. Yet – unbeknownst to the delegates – the Parliament always takes whatever action got the most votes: this way we avoid paying the cost of the randomization!)

The idea here is that moral theories get more influence the more probable they are; yet even a relatively weak theory can still get its way on some issues that the theory think are extremely important by sacrificing its influence on other issues that other theories deem more important. For example, suppose you assign 10% probability to total utilitarianism and 90% to moral egoism (just to illustrate the principle). Then the Parliament would mostly take actions that maximize egoistic satisfaction; however it would make some concessions to utilitarianism on issues that utilitarianism thinks is especially important. In this example, the person might donate some portion of their income to existential risks research and otherwise live completely selfishly.

I think there might be wisdom in this model. It avoids the dangerous and unstable extremism that would result from letting one’s current favorite moral theory completely dictate action, while still allowing the aggressive pursuit of some non-commonsensical high-leverage strategies so long as they don’t infringe too much on what other major moral theories deem centrally important.

In a comment, Bostrom continues:

there are a number of known issues with various voting systems, and this is the reason I say our model is imprecise and under-determined. But we have some quite substantial intuitions and insights into how actual parliaments work so it is not a complete black box. For example, we can see that, other things equal, views that have more delegates tend to exert greater influence on the outcome, etc. There are some features of actual parliaments that we want to postulate away. The fake randomization step is one postulate. We also think we want to stipulate that the imaginary parliamentarians should not engage in blackmail etc. but we don't have a full specification of this. Also, we have not defined the rule by which the agenda is set. So it is far from a complete formal model.

It's an interesting idea, but clearly there are a lot of details to work out. Can we formally specify the kinds of negotiation that delegates can engage in? What about blackmail or prisoners' dilemmas between delegates? It what ways does this proposed method outperform other ways of dealing with moral uncertainty?

I was discussing this with ESRogs and Stefan_Schubert at the Effective Altruism summit, and we thought it might be fun to throw the question open to LessWrong. In particular, we thought it'd be a good test problem for a Polymath-project-style approach.

How to Polymath

The Polymath comment style suggestions are not so different from LW's, but numbers 5 and 6 are particularly important. In essence, they point out that the idea of a Polymath project is to split up the work into minimal chunks among participants, and to get most of the thinking to occur in comment threads. This is as opposed to a process in which one community member goes off for a week, meditates deeply on the problem, and produces a complete solution by themselves. Polymath rules 5 and 6 are instructive:

5. If you are planning to think about some aspect of the problem offline for an extended length of time, let the rest of us know. A polymath project is supposed to be more than the sum of its individual contributors; the insights that you have are supposed to be shared amongst all of us, not kept in isolation until you have resolved all the difficulties by yourself.  It will undoubtedly be the case, especially in the later stages of a polymath project, that the best way to achieve progress is for one of the participants to do some deep thought or extensive computation away from the blog, but to keep in the spirit of the polymath project, it would be good if you could let us know that you are doing this, and to update us on whatever progress you make (or fail to make).  It may well be that another participant may have a suggestion that could save you some effort.

6. An ideal polymath research comment should represent a "quantum of progress".  On the one hand, it should contain a non-trivial new insight (which can include negative insights, such as pointing out that a particular approach to the problem has some specific difficulty), but on the other hand it should not be a complex piece of mathematics that the other participants will have trouble absorbing.  (This principle underlies many of the preceding guidelines.)  Basically, once your thought processes reach a point where one could efficiently hand the baton on to another participant, that would be a good time to describe what you’ve just realised on the blog.

It seems to us as well that an important part of the Polymath style is to have fun together and to use the principle of charity liberally, so as to create a space in which people can safely be wrong, point out flaws, and build up a better picture together.

Our test project

If you're still reading, then I hope you're interested in giving this a try. The overall goal is to clarify and formalize the Parliamentary Model, and to analyze its strengths and weaknesses relative to other ways of dealing with moral uncertainty. Here are the three most promising questions we came up with:

  1. What properties would be desirable for the model to have (e.g. Pareto efficiency)?
  2. What should the exact mechanism for negotiation among delegates?
  3. Are there other models that are provably dominated by some nice formalization of the Parliamentary Model?

The original OB post had a couple of comments that I thought were worth reproducing here, in case they spark discussion, so I've posted them.

Finally, if you have meta-level comments on the project as a whole instead of Polymath-style comments that aim to clarify or solve the problem, please reply in the meta-comments thread.