What? A blockchain isn’t a distributed ledger. A blockchain IS a chain of linked documents - whereas these documents are usually hash trees including the “transactions” per block. They ensure integrity by hashing the previous blocks. The proof of work is just a way to ensure a self regulating growth of virtual currencies and to prevent double spending.
>A blockchain isn’t a distributed ledger. A blockchain IS a chain of linked documents
You are interpreting "blockchain" to be constrained to a "chain of hashes". That is a valid interpretation.
The parent (Uptrenda) is interpreting "blockchain" as a umbrella label for "distributed ledger". This wider definition is also a valid interpretation and this language phenomenon is called "synecdoche"[1].
To point back to the actual article, the author (Gerald Nash) is using "blockchain" in both meanings. On the one hand, he talks about the wider scope of distributed currency... but on the other hand, his Python example is constrained to a "chain of hashes". Since Mr Nash is mentioning the Satoshi bitcoin whitepaper when talking about "blockchain" (the wider meaning), Uptrenda's criticism is reasonable because the most interesting part of distributed-blockchain is the invention of incentives (mining rewards) and social agreement on acceptable hashes (e.g. how many 0000s are counted, which chain is chosen, etc).
As other distributed projects such as IPFS/Diaspora/Sandstorm/etc show, finding the right combination of incentives to create social buy-in and sustainability is the hard part. The hashes is the easy part.
That argument is not exactly valid, because the concept of a block chain has been described a long time before it was used in "virtual currencies." [1]
"Block chains" in modern times are very helpful in handling transactions in databases by replacing things like CAS-Numbers [2] with hashes. The hash of the previous block effectively becomes the CAS-Number, with the feature of staying persistent and verifiable.
CAS example: IF X_version IS 200 SET X=2
BC example: IF hash(X) IS 200 ADD document Y WITH Y_parent = hash(X)
That is, while the article does in fact also mentions Bitcoin, I don't see a point in discrediting the article, the code or the author in any way. Personally, I find it far more valuable for engineers to understand the underlying, fundamental concepts of things before going all-in. Sure, he could have discussed all these things, but for people who are new to the topic, that would not have been very helpful in understanding the concept of a block chain.
>, because the concept of a block chain has been described a long time before
Citing historical usage and original meanings is not relevant as to why people use synecdoche.
The point is that in today's discourse, the term "blockchain" has already expanded beyond the original literal technically constrained meaning of "chain of hashes". Even if _you_ want to keep the original meaning of "blockchain", you still have to recognize when _others_ are using synecdoche.
To interpret those articles correctly, you have to mentally substitute "blockchain" with "distributed ledger". If you substitute with "chain of hashes", the articles make no sense.
Synecdoche throws original historical usage out the window.
>, but for people who are new to the topic, that would not have been very helpful in understanding the concept of a block chain.
There are many web articles that create a "toy" blockchain by showing _hashes_. The problem is that the abundance of such articles actually hides the real ingenuity of the Satoshi/bitcoin.
Again, the hard part is combining multiple technologies in clever ways that can synchronize the psychology of anonymous people -- aka "decentralized trust". The hashing is the least interesting component of all that. However, since the "hashes" are the most "accessible" part of it (especially to programmers), that's what everybody ends up writing about! This has the unintended side effect if hiding the more groundbreaking ideas (the psychology) of distributed ledgers.
The psychology aspect is a part that's the most impressive. You have incentives -- everybody likes money -- and proof-of-work -- consensus that solves the byzantine generals problem. But if you combine them all to produce a new trustless kind of money then this innovation itself serves like a socially scaleless memetic payload.
It's like what Nick Szabo talks about in his social scalability article. That the design of Bitcoin offers high social scalability, allowing anyone to participate in the system across cultures, languages, customs, and laws. It kind of ties everything together under a single model.
I also agree with you about the "Synecdoche" thing, too. It seems like we're arguing about the same thing. As you say, you can interpret "blockchain" as the chain of blocks that is outputted from the consensus system or as the whole system itself. But I guess in the context of this article it was confusing whether this poster was having a genuine misunderstanding or was just talking about a part of the system.
> That argument is not exactly valid, because the concept of a block chain has been described a long time before it was used in "virtual currencies."
The idea of a "block chain" had a name back then and it still has a name now. No software developer would confuse a hash list with the underpinnings of a virtual currency unless:
A) You're writing a title for an article and want more clicks
B) You're a banking institution that wants to seem "hip"
C) You're working on a centralized database but really need funding so you throw in the word "blockchain"
D) You're a reporter and you have no clue what you're talking about
Show me anyone referring to a "block chain" in a non virtual currency context that doesn't fall into the above categories and I'll reconsider.
I see what you mean. It's amazing how people on Hacker News always know the exact word for a concept no matter how obscure. I learn more from the comments here than I do from the articles.
This is a really twisted take on blockchains. The whole point behind a blockchain is that cryptoeconomic incentives serve as an additional security function which is better than relying on generosity alone to contribute hashing power. So while it is true that a blockchain can exist without any kind of currency - the real genius behind blockchains is how they are designed as a new kind of corporation - one which requires no trust to pay users to create a single, shared view of an ordered list of events.
It's kind of like how in modern cryptography most of our algorithms aren't bullet proof. Cryptographers aren't saying that an algorithm can't be broken, but that it requires so much computational resources to do so that its simply improbable. We can say that blockchains also include this idea but they add the economic aspect; Now it isn't just improbable to break an algorithm (with universe sized computers) -- its also improbably (and irrationally) expensive.
Your other point is that a blockchain is simply a linked chain of documents. This is incorrect. The whole point behind a blockchain is that it serves as a way to get people to agree on an ordered list of events. The problem was never being able to form that list (anyone can hash a list of documents, its basic applied crypto.) It was getting a group of strangers to agree on a single result under highly adversarial conditions.
> The whole point behind a blockchain is that cryptoeconomic incentives serve as an additional security function which is better than relying on generosity alone to contribute hashing power.
This has nothing to do with blockchains. What you're describing is proof of work with a payout system, and you could implement that without a blockchain at all.
>So while it is true that a blockchain can exist without any kind of currency
It has always been true. This was, in fact, exclusively the case before the first cryptocurrencies - blockchains are data structures, not a concept exclusive to currency.
>Your other point is that a blockchain is simply a linked chain of documents. This is incorrect.
It is exactly correct. The use of blockchains in cryptocurrencies is irrelevant to what they are. If I build the next great money machine tomorrow using a doubly-linked list, it doesn't change what a doubly-linked list fundamentally is. The fact that many people have been introduced to the idea of a blockchain through cryptocurrencies doesn't alter the basic facts.
>The whole point behind a blockchain is that it serves as a way to get people to agree on an ordered list of events.
This is not what the blockchain does. The blockchain helps to ensure that Proof of Work is effective for maintaining consensus after blocks are made - it's the role of PoW to produce the agreement. A blockchain without PoW would allow members to produce new combinations of blocks at will to edit the history.
Okay, lets argue that a blockchain is simply a data structure to create a linked list of hashes... Do you know what's part of that data structure as defined in the original paper: the format of a new block hash (how many zeros it has.) It's the fingerprint of a block that decides how to extend the chain. So if you simply decide to build a linked chain of blocks without any regard to the format of block hashes (proof-of-work) and the total accumulative hashing power, then it makes no sense at all.
Like I said: you can't just abstract this part away as a "data structure" and still have it mean anything. Without proof-of-work your toy example is literally just a made-up document sitting on a single computer.
>blockchains are data structures, not a concept exclusive to currency.
Blockchains as a linked list of hashes don't make sense. You need proof-of-work to decide on the chain. Proof-of-work is expensive so without the currency, proof-of-work doesn't make sense. There are other ways to agree on the order of events but they are not blockchains as understood by the experts in this space (and removing any one of these things undermines the benefits.)
Journalists and enterprise "blockchains" enthusiasts are free to use the term however they like but it doesn't change the fact that blockchains were introduced as an incentivized, trust-free ledger of value -- and by removing any one of its parts the benefits are still lost.
>This is not what the blockchain does. The blockchain helps to ensure that Proof of Work is effective for maintaining consensus after blocks are made - it's the role of PoW to produce the agreement. A blockchain without PoW would allow members to produce new combinations of blocks at will to edit the history.
Blockchains use proof-of-work to create agreement and pay anonymous contributors for doing the work to do so, its as simple as that. A "blockchain" without either of these things is not a blockchain. Incentives are needed to improve social scalability and ensure that there is a reason to continue to secure the ledger.
Proof-of-work is used to give the chain its meaning. I could hash a list of documents right now that said I had millions of dollars but this list couldn't be used by anyone else in an untrusting network of computers without a consensus algorithm... It just so happens that proof-of-work is still the most secure way to do that consensus. So you cannot abstract it away as a "data structure" independent from proof-of-work and the incentives that drive it...
The argument you're trying to make about "blockchains" is something I've only seen enterprise blockchain enthusiasts make about ledgers, and these people usually don't understand the system very well so they end up taking parts of the blockchain away and building something that makes little sense in the end (sometimes its an improvement but usually not.)
