Bitcoin money ≠ the Gold Standard.

It is difficult for me to fathom an environment where bitcoin is more attractive than gold or silver. At least outside of the alternate universe of PR that bitcoin proponents seem to live in.

Bitcoin claims to share the attributes of metals that make it different (ie. immutability, scarcity), but does so in a way that is impenetrable to the average person with the added flair of having do go through anonymous and shady middlemen to exchange bitcoin for an alternate currency in a highly volatile market.

So other than making the early bitcoin users who likely hold most bitcoin rich, what is the advantage of using it over other physical commodities whose use has been established for millennia?

There's a lot of disagreement over that word "voluntary", though. People who emphasize the "capitalism" part, as in anarcho-capitalists, tend to take a very loose view of what constitutes voluntary agreement, which is basically anything short of initiating actual physical violence, or perhaps direct threats like putting a gun to someone's head. Others, from the more left-leaning parts of voluntaryist circles, require a stronger definition of voluntary.

The standards of traditional western contract law for what counts as a voluntary agreement (i.e. not one entered into under coercion or duress) are somewhere in between.

True, but that's a problem of semantics which is not specific to the definition of capitalism. Whatever system you advocate, you'll have to define the terms you employ: "person", "market participant", "proletariat", "equality", etc.

I haven't seen this mentioned yet, so I'll mention it here:

The production curve for bitcoin, that starts steep and eventually levels off when total supply reaches 21M, is not at all like gold:

http://www.goldsheetlinks.com/production2.htm

At times gold production has exceeded population growth, at times it has lagged behind, but it certainly has not leveled off.

Also recall that Friedman called for a fixed 3% growth in the money supply, year on year, commensurate w/ long term rates of economic growth. So why would Bitcoin use a curve that starts steep and levels off?

I have heard two claims from Gavin: 1) it represents the pattern of natural resource extraction (easy it first, progressively harder until the marginal cost exceeds the margin gain), and 2) it encourages early adopters.

Now, I might wish it weren't so, but we're really good at natural resource extraction, and we get better over time, until demand falls. Plus, the general thinking goes, money supply should ideally grow at a constant rate, in line w/ long term economic averages. Maybe the extended long term view would restate that as a constant rate, relative to population growth. I don't know. The system has to reach equilibrium eventually, but we're not there yet, and for now the closest approximation is a constant percent, year-on-year.

So I'm afraid that reason (1), and Bitcoin resembling something fundamental in nature and the economy, is just not true. At best, Bitcoin is an entirely new kind of monetary system, with properties that don't resemble the gold standard or fiat currency, but will be beneficial in some fashion down the road. And at worst, it's just a Ponzi scheme.

I haven't seen (1) addressed substantively, so for now I'm tending towards bitcoin-as-ponzi-scheme.

So, the claim of being P2P goes to the wind first :)

Second. When accepting a coin, a node needs to check the coin was not spent since the last time it changed hands. If the buyer claims he got it 1 month ago (and shows a proof), then the seller needs to check a month worth of transactions, just in case it was double-spent. Note the terrible asymmetry of the attacker's and the defender's costs.

Third. Today I had to reread the paper (by Nakamoto) and I am surprised (again) by the level of wishfulness and naïveté. Sec 5 (page 3) says: "the nodes that were working on the other branch will then switch to the longer one". Does he realize that in a distributed system nodes might have totally different opinions on the number and length of those branches? And that those opinions might change. It is easy to imagine nodes hopping between branches with no global agreement possible. His very way of thinking has zero intuition about distributed/asynchronous systems, sorry.

Obviously, that may be cured by introducing well-provisioned central sites, as you say. But then, all that crypto-trickery becomes entirely meaningless and the system loses its raison d'être. Well-provisioned mutually-recognized sites/banks may do it exactly the way they do it these days.

Sorry for the rant.