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December 01, 2005


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Jon Jenkins

You seemed to leave out consensus methods such as the Quakers and facilitated decision making processes.

Christopher Allen

My intent was more to outline the broad categories of collective choice, then to give all the possible examples within each category. Both consensus methods and facilitated decision making processes fall under the "deliberation systems" category.

It is my hope in future articles to dig deeper into each broad category and show more examples of types. Next week hopefully will be comparison rating systems.


You should take a look at Jeff Vails' writings on rhizome networks as counter weights to hierchical power structures. http://www.jeffvail.net/2005/08/rhizome-communication-and-our-one-time.html

There's a connection between your ideas and his that I can't quite articulate because my mind is focussed elsewhere at the moment. But I shall return.

Christopher Allen

I've made some changes to this blog entry, adding consensus systems under deliberation systems, added reputation systems as a type of opinion system, simplifying some of the category names, and added some links.

F. Randall Farmer

This is an excellent summary, but I feel like I want a comparison table of some kind.

Would "information futures market" or the like be a Delphic system? It sure seems more like a consensus measuring device to me.

One of the most interesting things about all of these systems is the side effects they have on the decisions made. Binary Votes polorize options. Information Futures Markets encourage results manipulation (by design!)


This is a wonderful overview. Thank you for putting it together!

I'd like to suggest one small correction to the description of Condorcet voting, which says "it is much harder on the voters, who have to rank every single candidate". In a Condorcet system, the voters don't have to rank every candidate; they can rank as many or as few as they want (just like IRV), and they can even rank candidates equally (unlike IRV). The Wikipedia article entitled "Condorcet method" describes this.

Regarding a comparison of these systems, i've tried to illustrate the behaviour of plurality, approval, IRV, and Condorcet elections at http://zesty.ca/voting/ , and i hope you will find my method and results interesting.


The problem of choice is outline very well in the book 'The Paradox of Choice' by Bary Schwartz. It provides a great description of some of the other challenges of multi-party elections. I found it very interesting when it got into the psychology of choice regret, and alternative choices.

nick szabo

I agree this is a very interesting article! I notice an (intentional?) lack of coverage of most of the dominant and mature decision-making institutions in our society: markets in general (and specifically institutions such as exchanges -- mentioned briefly -- auctions, fixed-price retail stores vs. haggling bazaars, and so on), risk sharing institutions (e.g. insurance), hierarchical organizations based on the employer-employee and boss-subordinate relationships, the judiciary based on written law, opinion, and precedent, and so on. Of course, it would be very ambitious to tackle these, but it would at least be interesting to try to categorize them according to your taxonomy. Perhaps they are so complex they often fall into multiple categories.

The systems you describe abstract a vast amount of diffuse and often tacit information pertinent to a decision into a numerical result. Most economists (particularly Austrian school) would argue that at least on a large scale prices generated by auctions and exchanges generally do this better than other collective decision making systems. On the other hand, many systems for collective choice don't work via an abstract numerical intermediary (e.g. the opinion and precedent system of the judiciary).

I suggest that the most important factor in these institutions is the costs involved in eliciting diffuse knowledge and lossily compressing it into a decision which is hopefully nevertheless a reasonably accurate reflection of that diffuse information.

Christopher Allen

At least part of the reason why I didn't strongly highlight markets is that the definition of "collective choice", at least as far as how many academics use it, is all the methods that groups make decisions EXCEPT markets. For instance, from http://www.bsos.umd.edu/umccc/ "models of individual rational choice behavior to study non-market social phenomena".

However, another definition is http://www.artsci.wustl.edu/~polisci/calvert/PolSci505/ "social choice theory and noncooperative game theory", and I might say that markets fall into a subset of noncooperative game theory.

Personally I'm not sure why most academics exclude markets, thus I do briefly mention the Stock Market as a subcategory of comparison system. I hope to mention them more in other future articles, in particular, prediction markets as a subcategory of Polling Systems.

Kare Anderson

Will you cover, in a future post the forced choice vote? I'd welcome learning about more ways that a group can discuss alternatives (online or in person) then either vote in a priority way (first choice, second choice, etc.)
and/ or choose to vote in a first round for "x" number of options then limit the conversation to those options, then perhaps do a forced choice vote.

In other words what are some hybrid methods that you
(amazing) Christopher might craft that combine:

A. Thoughtful conversation to hear all ideas/opinions -
without the downsides of :
• being prolonged to the point it pains participants
• being dominated by one or two "strong" or verbose personalities


B. Stages of voting closure that enable all participants
to see 'we' are moving to the top choice(s) of the group

- another fan of life with alacrity

p.s. In addition to the aforementioned, brilliant, The Paradox of Choice, read Smart Choices by Howard Raiffa

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