Trust, Consensus and Truth.

The Blockchain approach to three of the fundamental issues of our time.

Blockchain technology has hit the headlines in the last few years thanks to the advent of Bitcoin. Bitcoin is a cryptocurrency and payment system that addresses and solves issues that have been considered, up to that point, unsolvable. In particular Bitcoin removes the need of a middle-man who acts as guarantor when two parties decide to exchange some monetary value, while securing the records of the transactions in a tamper-proof, distributed ledger.

From Trust to Trustless Consensus

When transacting monetary value, the role of guarantor has been traditionally played by banks; yet, history has shown us that the trust we endow these institutions with is not necessary well placed. Bitcoin introduced a mechanism based on cryptography that allows transactions to be validated and recorded without the need of a trusted third party. For this reason Bitcoin is referred to as a “trustless” payment systems. This trustlessness is based on an algorithm called consensus protocol, which constitutes the core of the blockchain technology. The consensus protocol and the ledger where the transactions are recorded are both shared by all the participants to the Bitcoin payment network (hence the term distributed ledger), so as to prevent arbitrary changes to the record of transactions by any ill-intentioned actor.

The notion of consensus is key to the trustlessness and the security of any blockchain-based solution, and it is a fundamental part of what makes the Bitcoin network a tamper-proof payment system.

It is virtually impossible to alter the record of the transactions once they have been verified by the participants of the network and added to the ledger¹. In other words, the ledger where the transactions are recorded is effectively immutable².

The properties of trustlessness and immutability introduced by the blockchain technology are not specific to monetary transactions, and can be applied to any exchange of value (or any interaction underlying an exchange of value) between two parties. This is why blockchain technology is expected to revolutionise so many sectors of our society; from the energy market, to the supply chain logistics, to conveyancing services, and so on. The bottom-line is that the transactions recorded in the (distributed) ledger by the blockchain’s consensus protocol are transparent, verifiable and immutable.

What makes a blockchain-based transaction legitimate?

I would like to spend a few words on the terms verifiable, valid and legitimate. In a blockchain-based payment system, a transaction is considered valid if every node in the network can confirm its legitimacy, i.e. if all the nodes (who share the same consensus protocol) can independently verify that the transaction was indeed authorised by the party who issued the payment³. The party receiving the payment is not required to provide any authorisation, as the recipient of the transaction is the one benefiting from receiving the funds.

In a different context, such as in a blockchain-based conveyancing service, it may be necessary to have both parties’ authorisation in order to verify the legitimacy of a “transaction”. In this case the word transaction must be understood as an interaction between two or more parties that involves the exchange of something that is valuable to all that are involved. An example can be the exchange of a contract for the purchase of a house. The buyer’s authorisation is necessary as he/she is the one providing the funds, and the seller’s authorisation is also needed as he/she is the one transferring the ownership of his/her house to the buyer.

This is not dissimilar to what happens traditionally outside of blockchain-enabled systems; whoever is involved in a transaction as the provider of some valuable asset (funds, a house, a service) must provide their authorisation for that transaction to be considered legitimate. The novelty introduced by blockchain-technology is that:

1. The transactions are authorised cryptographically and verified automatically by the network through a software (the consensus protocol) that performs the necessary checks, hence removing the need of a middle-man;
2. Once verified, the transactions are stored in a distributed ledger that is immutable.

Consensus and Immutability vs Truth.

This section will take quite a philosophical turn, and try to examine the claim made by some blockchain enthusiasts about the possibility of using this technology to address, pursue and secure nothing less than truth itself.

John McAfee says that, because “the blockchain is an immutable record of what has happened, […] for the first time in human history […] we have the truth available to us”. This is a big statement, and it surely holds true when it comes to transactions where two or more parties have complementary interests at stake (as in the example of purchasing a house, where someone is interested in receiving the money and someone else in receiving ownership over a property). But does this statement remain true in all possible scenarios?

Example 1: Blockchain and Criminal Records

Let’s consider the case of criminal records. In an article titled “CRAB: Blockchain Based Criminal Record Management System”, Tasnim et al. argue that “by incorporating criminal records in a blockchain, authenticity and rigidity of records can be maintained; which […] helps prevent unlawful changes in the data”. They also add: “Authorities (e.g., Law enforcement agencies and courts) will be able to add and access criminal data. General users (e.g., selected organizations and/or individuals, airports, visa application centers etc.) will have access to the data so that they can look up criminal records”. This sounds like — and probably is — a very good idea. However, there is an element that has been partly removed from the equation: the consensus. Records will be added to the “ledger” by a very limited and specific set of actors (the authorities in charge for the case). Obviously this is not a bad thing; we need the specific competences of the judicial system’s representatives to make informed deliberations on whether the incriminated acts really occurred and whether those acts are lawful or not. It is important to notice, however, that

the notion of consensus — which is central to blockchain technology — is here at least partly replaced with the notion of appeal to authority.

The consensus is still central to ensure the immutability of the criminal records on the blockchain (see this article for more details), but not to add those records in the first place.

When it comes to blockchain technology, the wider the consensus about the validity of a certain record (transaction), the better, because this is as close as it gets to proving the legitimacy/veracity of that record⁴. But this only works if the parties involved in that transaction have complementary interests at stake. In the case of the judicial system, this is surely not the case as the defendant and the prosecutor have obviously opposing interests, and there are no apparent complementary interests among the different members of the court or even between different courts. In other terms, in the case of the judicial system, blockchain technology can provide an excellent way to securely preserve data about criminal records, but not to verify the legitimacy of such data.

The ledger of criminal records is a record of “truths” insofar the judgements expressed by the courts are devoid of fallacies and errors.

This is a domain where blockchain technology would not bring about truth, but only a verifiable and secure record of court rulings. Here, the element of trust must still be included in the equation for us to consider that record as an accurate indicator of the underlying factual events.

Example 2: Fake-News, Accountability and Social Consensus

There seems to be little doubt that we live in what many have described as a post-facts world. Traditional media has often been accused to be biased and ideological motivated. Alternative media — where individuals not associated with any particular news outlet go in search for evidence substantiating/refuting the headlines of the moment — often did not proof to be any more trustworthy or less susceptible to those same biases. In addition to this, social networks have become the place where a growing number of people form their opinions based on rumours, memes and unverified statements about everything that (supposedly) happens under the sky. No surprise that the term “fake-news” has become so popular in our daily language.

Is it possible for blockchain technology to tackle this issue effectively by providing a system where news can be securely stored and its authenticity verified? Many believe so. The New York Times, for example, is devising a blockchain-based solution to combat misinformation and adulterated media⁵. Other news outlets, institutions and companies are also trying to tackle the issues of news authenticity and its safe storage, such as Orange⁶, Leeway Hertz⁷, DV Pollen⁸, The University of Sussex⁹ (UK) and the Information Technology University of Lahore¹⁰ (Pakistan), just to name a few.

The common denominator of all these approaches consists of verifying the provenance of any source of digital media by storing a news item’s metadata on a blockchain (e.g. when and where a photo or video was shot, who took it, how it was edited and who published it). However, some aspects of the solutions proposed tend to divert from the original conceptual pillars that characterise blockchain-based systems.

Adnan Qayyum et al¹⁰, for example, introduce the notion of Honest Miner Nodes and Trusted Entities (identified as “credible mainstream media outlets”) as guarantors of the trustworthiness of the blockchain’s content. Although done with the intention of providing the best and most professional service possible, this solution reintroduces the concept of trust towards an authority, which is what the blockchain originally aimed to avoid. Those mainstream media outlets are not immune from the suspicion of bias or even lack of professional integrity.

Huckle and White⁹ also note — in relation to their work — that while their “application has the potential to be able to verify the originality of media resources […] technology is only capable of providing a partial solution to fake news. That is because it is incapable of proving the authenticity of a news story as a whole.”

In addition to this, it is not far fetched to imagine the emergence of competing blockchains where news are reported or not depending on whether they serve or hinder specific political agendas. The original problem of establishing a repository of trustworthy news would then translate — at least partially — into a problem of competing world-views that are based on partial truths, which is very close to what we already have right now.

Conclusions

From what I can see, blockchain technology cannot be considered the ultimate reference of truth in all imaginable contexts. I also think that this inability is not due to a temporary limitation of the technology, but that it has a more fundamental cause.

In the absence of complementary interests at stake, blockchain technology — although still capable of providing us with an excellent way of securing records — does not turn to be the ultimate tool for discerning true from false.

If I’m right in my understanding, I wonder whether this fact is a bad or a good thing. For techno-enthusiasts and truth seekers alike there are obvious reasons to be disappointed about this (likely) broken promise of the blockchain phenomenon. However I also believe that total reliance on an external and ultimate reference of truth — although algorithmically sensible — is not healthy for our psyche and intellect.

All in all, it seems to me that we cannot completely prescind from the human element in the pursue of truth; and this is fundamentally a good thing. The risk of becoming lazy in our attempt to understand and make sense of our world is very real, and is arguably the cause of the deep divide and cultural polarisation that seem to characterise our times.

Blockchain technology can surely help us discerning the truth, but it should not make us feel exempted from our right/duty to continuously sharpening our ability to read, understand and make sense of the reality we live in.

Notes and references

1. Here the word “impossible” must be understood in probabilistic terms. It would be more accurate to say that it is extremely unlikely that someone could tamper the Bitcoin’s ledger. However, the chances that a malevolent attempt to alter the system is carried out successfully are so unfathomably thin (at least for an established blockchain-based payment system such as Bitcoin) that the use of the word impossible seems to be completely justifiable.
2. The reason why the distributed ledger of a blockchain-based network is considered immutable has been exhaustively illustrated in one of my previous articles. Here I will just ask the reader to either refer to that article or to just trust me (quire ironically :-) ) on this.
3. More precisely, the issuer “signs” the transaction certifying the ownership of the bitcoins he/she is about to sent to the recipient.
4. In particular, an agreement from all the participant to the network have to be reached for a record to be considered valid.
5. The News Provenance Project is exploring new ways for publishers to help fight misinformation.
6. Orange takes steps to fight fake news with blockchain.
7. Combating fake news and reaching to its origin.
8. Using Blockchain and Machine Learning to Fight Fake News.
9. Fake News — a Technological Approach to Proving the Origins of Content, Using Blockchains
10. Using Blockchain to Rein in The New Post-Truth World and Check The Spread of Fake News