On Green's challenge of "I postulate that no one has ever said “Here is a problem that I have. Oh look, blockchain is a good solution.” in 2015 I worked in dig

On Green's challenge of "I postulate that no one has ever said “Here is a problem that I have. Oh look, blockchain is a good solution.” in 2015 I worked in digital identity and showed how identity itself in its very definition was the emergent artifact of relationships, and the only way to establish idenitity in a consistent and scalable way was to federate the consenus of which your identity was the artifact. The company abruptly pivoted from its federation protocols based ID to an identity blockchain, and it is being adopted by governments and financial institutions today. The next problem was "how do you do cryptographic key management in autonomous swarms of devices that connect via a mesh protocol that cannot connect to a central base station?" again, this is the same identity problem, where the integrity and quality of "legitimacy" of a node's identity is an artifact of the consensus of the mesh it connects to. Now, these cases don't need proof of work, but they absolutely rely on consensus, and not a database. Their criticisms of blockchains imply a misunderstanding of a core aspect of security, which is that a proof in a closed loop system cannot be shown to be externally consistent with another instance of itself without some encompassing closed loop system both instances are a part of. A generic consensus protocol (like a blockchain) enables the federation of these consistency proofs. This particular blockchain may not be the best possbile one - but I'd argue back that a cryptographic substrate that facilitates consensus and federation for distributed computing is as significant an invention as the internet. There is another piece where it's finally clicking that "security" isn't so much an engineering problem as it is a critical theory of technology based on different ideologies that favour autonomy or governmance respectively, and like a critical theory, it can be used to both befog and obfuscate - or prove - whatever you like in it. On currencies, to borrow an adage, if you don't know what problem cryptocurrencies are solving, the problem may be you. That's unnecessarily provocative, but the real problems it solves are those around peer-to-peer transactions and dynamic federation - all the stuff the internet used to promise until it succumbed to the very criticisms Schneier is making of blockchains, particularly emergent centralization and scams. I have tremendous respect for both of them, but Schneier and Green are both making appeals for governance to people who don't want it, and I think they are lending their engineering cred to a general global governance narrative that I'm not sure they appreciate the motives of.