Blockchain as a Database: Implications for Money and Ledgers

This article explores blockchains as a specialized form of database, contrasting them with traditional financial accounts and examining their broader implications for monetary systems and economic activity.

Blockchain as a Database

A blockchain is fundamentally a ledger used to store information about transactions, making it a type of database. Data is stored in signed blocks, which are linked to each other, forming an immutable chain of interconnected entries. For Bitcoin, each node attempts to bundle incoming transactions into a new block. These blocks contain a timestamp, a nonce (for proof of work), a hash reference to the previous block, and a list of transactions.

Messages within the blockchain are encoded with public and private keys, ensuring that transactions cannot be impersonated. These keys commit to a transaction, preventing it from being undone. Transactions primarily involve the transfer of "coins" from one account to another, recorded in groups on the ledger.

The Genesis of Bitcoin

Bitcoin was registered on August 18, 2008, followed by a white paper titled "A Peer-to-Peer Electronic Cash System" by Satoshi Nakamoto. The open-source code was released in January 2009. Nakamoto mined the first block, the "genesis block," on January 3, 2009, creating the Bitcoin network. Nine days later, Hal Finney received the first Bitcoin transaction from Nakamoto. In May of the same year, Bitcoin was used for a commercial transaction to buy pizza, an event now known as "Bitcoin Pizza Day."

According to computer scientist Arvind Narayanan, while individual components of Bitcoin existed in earlier literature, their complex interplay resulted in the first decentralized, Sybil-resistant, and Byzantine fault-tolerant digital cash system.

Blockchain and Money: A Broader View

The concept of a "peer-to-peer electronic cash system" raises questions about the nature of money. Paul Krugman's "babysitting economy" anecdote illustrates this: a group of congressional staffers in the 1970s used certificates for babysitting services. These certificates functioned as a form of money, earned by providing a service and then used in exchange for another. However, issues arose when participants hoarded certificates, leading to a collapse of the system, which Krugman attributes to a conflict between money's role as a medium of exchange and a store of value.

Central banks initially viewed Bitcoin with skepticism. Hyun Shin of the BIS stated in 2018 that cryptocurrencies "cannot scale with transactions demand, are prone to congestion, and greatly fluctuate in value," concluding that their decentralized technology is a "poor substitute for the solid institutional backing of money."

However, the landscape has shifted. By 2023, Augustin Carstens and BIS staff, in their paper "The Future Monetary System: From Vision to Reality," acknowledged the fragmentation of existing financial systems and proposed a "unified ledger" to knit together transactions and operations. While still emphasizing the "singleness of money" (referring to central bank fiat money), this indicates a recognition of blockchain's platform potential. The paper suggests that a unified ledger could overcome the inefficiencies of legacy systems, where money and assets reside in separate proprietary databases patched together by complex messaging systems.

The idea of a "singleness of money" is challenged by the existence of multiple national fiat currencies. While some propose a super-currency, economic theory suggests that for cross-border platforms, only a unit of account is necessary, not necessarily a store of value or medium of exchange. This evolving perspective highlights that the conversation has moved beyond simply dismissing Bitcoin to exploring how blockchain technology can be integrated into domestic and international monetary systems.

Financial Accounts as Databases

Financial accounts, like those used by households or corporations, also function as databases. They typically consist of three interconnected statements: an income statement, a cash flow statement, and a balance sheet.

Every transaction impacts these accounts. For example, wage income increases cash (an asset on the balance sheet), is recorded as revenue on the income statement, and contributes to net income on the cash flow statement. Similarly, paying a telephone bill is a cash outflow for consumption. Depositing cash into a credit group is an asset swap, not affecting the income statement.

The cash flow statement categorizes cash flows into: - Production: Inflows from selling goods/services, outflows for inputs. - Consumption and Investment: Spending on goods, services, or investments. - Financing: Changes in deposits, borrowing, and gifts.

A crucial aspect of financial accounting is consistency: the change in cash holdings on the cash flow statement must match the change in cash on the balance sheet. This principle, akin to double-entry bookkeeping, ensures accuracy and helps identify missing transactions.

Multi-Dimensionality and Payment Matrices

Blockchains and financial accounts are multi-dimensional databases, capable of including contracts and various objects beyond just money. Money, in this context, can be defined as an object that appears frequently in exchange or has a high velocity (high turnover relative to its stock). This definition applies to both blockchains and financial accounts and allows for the coexistence of multiple "monies."

Examples from Village India show payment matrices where goods, services, IOUs, grain, and currency are exchanged. Grain, for instance, can be used to pay for labor, illustrating a dual monetary economy where real goods coexist with traditional currency.

In the US, the Boston Fed's work on analog financial accounts for households reveals complex account flows, distinguishing between various forms of cash (currency, demand deposits, debit accounts, foreign currency). These flows demonstrate how different "monies" are used and converted, with many ultimately linked, directly or indirectly, to central bank liabilities.

Individual vs. Common Accounts

The concept of individual accounts versus common, distributed ledgers is critical. In the context of the Thai villages, enumerators recorded individual household transactions. While these were private, they could have been aggregated into a common, distributed ledger, similar to how Bitcoin operates. This would involve pooling recorded transactions, validating them, and then redistributing the common database to households.

A key advantage of a common, distributed ledger is its ability to reconcile discrepancies quickly. In the Thai data, it was common for a transaction reported by one household (e.g., a purchase) not to be reported as a sale by the other party. Traditional financial markets also face this, with lengthy end-of-day reconciliation processes. Distributed ledgers, by design, aim to resolve these inconsistencies in near real-time.

Formal Definition of a Distributed Ledger

A distributed ledger (DLT) is a technological infrastructure and protocols that enable simultaneous access, validation, and record-keeping across a networked database. Blockchains are a type of DLT, distinguished by their specific validation algorithms. DLTs reduce the need for auditing and enhance reliability by allowing users to view changes and their origins. While the concept of distributed computing is not new, advances in data science and technology have made DLTs far more capable.

Tensions: Individual vs. Community Perspectives

Central Bank Accounts and Real-Time Gross Settlement

Research on central bank real-time gross settlement systems highlights a conflict: banks know their payment obligations but can choose when to report them. This often leads to delays, as banks prefer to receive payments before making them, resulting in payment bunching at the end of the day. This behavior, driven by liquidity management, can be inefficient.

The inherent fragility of payments stems from a conflict between money's role as a medium of exchange and a store of value. Payments occur when reserves are abundant; otherwise, history-dependent equilibriums can emerge, as seen in Krugman's babysitting economy where coupons were hoarded rather than spent.

Double-Entry Bookkeeping and Community Currencies

Luca Pacioli, credited with formalizing double-entry bookkeeping, viewed money as a liability rather than an asset. He saw it as an obligation to the community, reflected in the use of "per" (debtor) and "A" (creditor) in accounting entries. This perspective emphasizes the social function of money.

Community Inclusion Currencies (CICs) are a modern example of this community-centric view. These mutual credit networks allow participants to give each other interest-free credit, often in the form of vouchers representing a promise against future production. The goal is to keep value circulating within the community, preventing "leakage" to external entities. Incentives are built in to encourage spending rather than hoarding. Notably, some CICs, like Sarafu in Nairobi slums, operate on blockchain platforms like Ethereum.

Technical Limitations of Blockchains

Despite their advantages, blockchains face technical limitations, notably the CAP theorem (Consistency, Availability, Partition tolerance). This theorem states that a distributed system cannot simultaneously guarantee all three: - Consistency: All users see the same data. - Availability: The system remains operational even if some nodes fail. - Partition tolerance: The system continues to function despite network failures that partition the system into isolated groups.

Blockchains, by their nature, often exhibit partition tolerance (e.g., conflicting blocks in Bitcoin before validation). This forces a trade-off: - Consistency and Partition Tolerance: Sacrifices availability (e.g., canceling operations to ensure consistency). - Availability and Partition Tolerance: Risks inconsistency (e.g., allowing operations to proceed in partitioned segments).

This "trilemma" means designers must choose which property to prioritize. Current payment systems can be mapped onto this framework: - Partitioned Accounts: Individual, potentially inconsistent accounts (e.g., Alice and Bob's separate ledgers). - Intermediaries: Centralized entities that provide a consistent view for some transactions (e.g., banks). - Consistent-Available Systems: Unique ledgers that provide consistent information (e.g., security depositories). - Sharding/Layer 2 Solutions: Attempts to improve scalability and availability by splitting ledgers or offloading transactions, potentially impacting consistency. - Compatible/Unified Ledgers: Efforts to integrate multiple ledgers, aiming for greater centralization and consistency.

Current Difficulties and Mapping Economies

Several challenges hinder the widespread adoption and effectiveness of blockchain and digital payment systems:

• Legacy Technology: Many traditional financial institutions still rely on outdated systems. While initiatives like FedNow offer instant payments, commercial banks often need to modernize their infrastructure or rely on concentrated aggregator payment system providers.
• Trust and Fraud: The promise of trustless systems in blockchain is often undermined by centralized exchanges and intermediaries, as exemplified by the FTX scandal where customer funds were misused.
• Unmeasured Currency: The use of physical cash, often unmeasured, presents challenges. Efforts to create digital currencies, like the digital dollar, grapple with balancing privacy with contract functionality.
• Data Silos: In many organizations, different departments (e.g., for payments, credit lending) maintain separate databases, making it difficult to unify data and gain a holistic view of customer transactions.
• Inconsistent Collection Mechanisms: Traditional surveys and macroeconomic data collection often lack the consistency checks inherent in double-entry bookkeeping, leading to discrepancies between different financial statements. This is evident in US micro and macro data, where cash holdings reported in cash flow statements often don't align with balance sheet changes.

To address these issues, there's a push to create consistent financial accounts. Projects are underway to develop templates that integrate electronic data (bank accounts, credit cards) with paper currency transactions to build comprehensive and consistent financial records for households and businesses. This effort aims to provide a clearer picture of economic activity, especially in dual economies where both digital and fiat money coexist, and where transaction costs and fraud can be significant.