All that's necessary for a proof system in a blockchain, as far as I know, is that mining be hard to do and easy to validate. Creating works of art is hard to do, but determining their value is relatively easy. The only issue I, who knows very little about blockchains, can find with this is that it would be quite slow. What are some issues that might come up with this, and is it generally plausible?

  • How would you determine a vote is valid (who votes, nobody voted twice) ? en.wikipedia.org/wiki/Sybil_attack :-) – darosior Apr 21 at 13:53
  • Well, you'd have to store votes on some other blockchain secured a different way, probably! I guess this couldn't possibly work on its own, but in conjunction with another, maybe...? – Seth Schmidt-O'Hainle Apr 21 at 14:03

These are not the only requirements.

The most fundamental requirement is that the PoW actually verifies something. It's not enough to do work and prove that you've done it - the work actually has to express acceptance of a specific branch of the block tree. Otherwise, it's useless in preventing double spending.

It follows that the problem to be solved must be generated from the details of a specific branch/block, and the proof must show that work was done with this specific block in mind. The work cannot be reused to signal acceptance of a different block. The block is baked into the work in the most fundamental level.

How would you do that for creative work? How do you generate creative assignments that are tied exclusively to some specific block? That's completely far-fetched. If the work is, say, a painting - once the work is done and the painting is drawn, it can just as easily be assigned to block A as it can to block B. It therefore verifies nothing.

Another requirement is that the work is not only verified easily, but also in a digital and decentralized way. Your software can, without any additional knowledge, computationally verify that some amount of hashing was put into a block. It cannot verify that someone who voted is indeed a human - it needs to rely on external trusted sources for that.

Which leads to the final point, which virtually everyone who proposes alternative PoW mechanisms miss - if there was a way to verify the identity of humans and collect their votes, there would not be a need to have proof of work at all. Instead of voting on works of art, they can just vote on which branch they think is right. This way they can synchronize transactions and prevent double spending. The whole reason we don't do that in Bitcoin, is that there is no way to verify identities in a decentralized, digital way, with the standards sufficient to reliably administer the voting. This is why we rely on independently verifiable proof of computational work.

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  • Thanks. I know so little about blockchains (I've read tons about them but it just never makes much sense to me) that this issue never even entered my mind. I have also had the idea of generating a logic puzzle from a block and having that be solved by a human, which could easily be checked by a computer - but the issue there is it could easily be solved by a computer as well... – Seth Schmidt-O'Hainle Apr 21 at 20:44
  • Maybe a jigsaw puzzle, since visual processing is harder for computers than for humans, but that isn't going to continue being true for much longer. So yeah... I guess this entire train of thought is hopeless... but, what actually stops decentralized digital verification of identity from being possible? Is there anyone trying to solve that? – Seth Schmidt-O'Hainle Apr 21 at 20:50
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    @SethSchmidt-O'Hainle: It's simply the fact that humans are not digital. Humans are physical beings that inhabit the earth. A computer connected to cameras etc. might be able to ascertain that someone is a human locally, but there is no way for it to convince other computers on the netowrk of this - they would think it just fabricates its input data. The advent of deep fake neural networks, which allow generating fake images of nonexistant humans, exacebrates the problem. – Meni Rosenfeld Apr 21 at 21:02
  • If no computer could do it, then no human could do it, either. I know this may seem pedantic but by that standard how do we know ANYONE is human? – Seth Schmidt-O'Hainle May 16 at 12:28
  • @SethSchmidt-O'Hainle: The distinction isn't between a computer verifier and a human verifier. Both are probably capable of convincing themselves that someone is human. Both are unable to prove it to anyone else. For a decentralized system to work, it must be based on proofs that anyone, anywhere can verify, even without physical proximity. There is also a distinction between a trusted verifier and a trustless verifier. We trust our government to issue IDs only to humans; but reliance on trust has no place in a decentralized system. – Meni Rosenfeld May 20 at 13:12

Only if you mean "something like" very, very loosely.

The entire logic of proof of work is that it is expensive to make, can be irrevocably, provably attached to a block quickly, and is cheap to rapidly verify automatically. How would human creativity voted on by other humans be irrevocably, provably attached to a block?

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