> How is the PoS model not "a list of transactions, and a protocol for deciding which transactions are allowed to be added to that list?"
It is. You seem to be the only one who thought the author said it isn't. He never did. He just said it's not a good one, because it's based on circular logic.
> I understand that the protocol itself is the source of controversy, but I don't understand why the author views PoS as circular but not PoW.
Because of the last step, "Who gets to decide which transactions are / which chain is valid?". In PoS that is "he who has the most coin". This will obviously lead to situations where Coiner A claims that Chain A -- where Coiner A has the most coin -- is the valid and correct one, while Coiner B claims that Chain B -- where Coiner B has the most coin -- is the valid and correct one, and Coiner C in turn claims that Chain C -- guess who has the most coin on that one? -- is... And so on and on.
Within the logic of each claim, that claim is of course the only possible and obviously correct one... But to you and me, if we are neither Coiner A, B, or C -- how do we choose which claim to accept? They all boil down to, in effect, "I'm right and I can prove it -- look, here's my proof, which is that I say I'm right." ("I have a chain which shows me having the most coin", which is the same thing.) That's the circular reasoning.
With PoW, in contrast, that proof is based on "I did more 'work' than anyone else", which is mathematically provable and (at least not as directly) self-referential in terms of "I have the most money because I say I have the most money, which proves that I have the most money."
(PoW is of course just about equally idiotic, only in another way: Proof that you have wasted precious resources and contributed to destroying the environment shows, not that you've created any value, but that you've destroyed it.)
It is. You seem to be the only one who thought the author said it isn't. He never did. He just said it's not a good one, because it's based on circular logic.
> I understand that the protocol itself is the source of controversy, but I don't understand why the author views PoS as circular but not PoW.
Because of the last step, "Who gets to decide which transactions are / which chain is valid?". In PoS that is "he who has the most coin". This will obviously lead to situations where Coiner A claims that Chain A -- where Coiner A has the most coin -- is the valid and correct one, while Coiner B claims that Chain B -- where Coiner B has the most coin -- is the valid and correct one, and Coiner C in turn claims that Chain C -- guess who has the most coin on that one? -- is... And so on and on.
Within the logic of each claim, that claim is of course the only possible and obviously correct one... But to you and me, if we are neither Coiner A, B, or C -- how do we choose which claim to accept? They all boil down to, in effect, "I'm right and I can prove it -- look, here's my proof, which is that I say I'm right." ("I have a chain which shows me having the most coin", which is the same thing.) That's the circular reasoning.
With PoW, in contrast, that proof is based on "I did more 'work' than anyone else", which is mathematically provable and (at least not as directly) self-referential in terms of "I have the most money because I say I have the most money, which proves that I have the most money."
(PoW is of course just about equally idiotic, only in another way: Proof that you have wasted precious resources and contributed to destroying the environment shows, not that you've created any value, but that you've destroyed it.)