I think that if a vote was free, no matter how much weight it carried, then it could be easily bought and the vote manipulated. If the cost of the vote was proportional to its weight, then it would be harder to manipulate the vote.
I know I haven't explained that thoroughly, but as an analogy think to how markets determine the clearing price for a good. Votes in markets cost money.

On 8 August 2015 at 16:10, Peter Todd <pete@petertodd.org> wrote:
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On 8 August 2015 11:03:04 GMT-04:00, Hector Chu <hectorchu@gmail.com> wrote:
>Thanks for this Peter. It is quite long winded and complicated so I
>just
>wanted to clarify one particular point. In John's proposal, are the
>coins
>actually locked up, or are they still freely spendable post-vote?
>Otherwise
>there is no real cost to casting votes. Locking coins up is related to
>the
>time-value of money and has a cost the longer they are locked up for.

John Dillon's proposal is essentially to have the economic majority give miners *permission* to raise the blocksize; making the vote costly is against the design intent of accurately capturing the broadest possible economic consensus.

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