"Consensus" was a word used in the distributed systems literature for all sorts of problems well before the Bitcoin paper. (As was "Sybil-attack-resistant", which is another phrase I ~used that was also in common use.) Bitcoin is interesting because it allows reasonably trustworthy consensus in a Sybil-attack-resistant way for a particular problem, namely, a distributed ledger that permits anyone to participate without permission from a central authority. There were lots of other systems for distributed consensus for other problems: a random example is BitTorrent.

I would actually dispute the definition of "cryptographically signed linked list" for Bitcoin. What makes Bitcoin blocks valid is not that they're cryptographically signed (signatures are over transactions, from the address that is trying to send money, but you can sign two different transactions and now you have double-spend). What makes them valid is the inclusion of a solution to the mining problem that incorporates the data being sent, and I think that in any context other than Bitcoin, "a message that includes a random nonce such that the hash has certain properties" wouldn't be called a "signature" at all. Take Hashcash, the proof-of-work system for email anti-spam that somewhat inspired Bitcoin: the web page and paper calls the authentication token a "stamp", and doesn't use the word "signature". The FAQ suggests an extension for mailing lists using the phrase, "A hashcash specific approach (avoiding signatures)".

I am super excited about CRDTs but they seem like an entirely unrelated problem space to Bitcoin, so using the term "blockchain" doesn't make sense to me. (In the same way that I am excited about DVCSes like git using Merkle trees to allow mergeable offline work without a central coordinator, but git is definitely not a blockchain.) That said, I did say this on an IRC channel the other day:

    < geofft> I would define "blockchain" as "a Merkle tree that solves the double-spend problem in a way that's resistant to Sybil attacks"
    < geofft> if your transactions commute, you don't have a double-spend problem, and therefore "blockchain" isn't meaningful
    < ...> geofft: doesn't stop people hawking blockchain solutions though :P
    < geofft> oh, sure
    < geofft> I would also define "blockchain" as "the word you should use instead of Merkle tree on your investor pitch"

So if that's your reason for using the word "blockchain," good for you :-)

I am reading through your Distributed Matters slides - exciting stuff and the point about ATMs not being strongly consistent is a very good one. Will need to reread a few times to make sure I get it!