When you abstract away the details, Bitcoin is an incredibly simple construct. It’s a piece of software that defines the existence of some 21 million fungible units -- i.e. bitcoins -- and the rules by which they ought to be distributed and exchanged. The software serves as a ledger, a record of who owns what and how many BTC. None of this, however, is what makes Bitcoin interesting let alone revolutionary. What makes it both of those things is that it’s a piece of software that is managed by and replicated across millions of otherwise uncoordinated computers all across the planet. This is what gives it its “decentralized” property, what makes it a money for and by the people, what makes it among the most secure computer systems in existence. What enables any of this is the notion of verifiability.

The notion of verifiability is just as it sounds -- it’s the capacity to verify things, to make sure a claim on reality is veridical. In the context of Bitcoin, verifiability means the capacity to verify the ledger of record, to ensure who owns what is in fact who owns what. What makes Bitcoin so powerful, indeed so revolutionary, is that it affords anyone who downloads the source code -- with very modest hardware -- precisely this capacity. This is what makes Bitcoin “trustless”. That is, it doesn’t demand one defer to the accounts of others or otherwise take a leap of faith. Simply run the code and see for yourself. It is in this sense that everyone in Bitcoin-land is a ‘first-class citizen’. There is no privileged authority with special access to state, which contrasts to the status quo of finance and money, where we remain subservient to the whims of banks and governments alike.

Verifiability -- specifically, end-user verifiability -- is thus a fundamentally egalitarian principle. It’s at the very core of what ought to set crypto apart from the fiefdoms of fiat and Web2. However, with the rise of next generation blockchains, like Solana and Sui, we’re seeing the real-time erosion of this essential value / feature. To be sure, this isn’t a knock on them, for end-user verification has historically come at a cost: throughput. Typically speaking, the easier you make it for anyone to run a “full node” and verify a chain, the less performant your system is bound to be. That’s because the primary way to make one’s chain easy to verify is to throttle the amount of throughput the system is capable of handling. For if a system isn’t dealing in significant data or computation, the system can be run on cheap hardware. This ensures end-user verification, but it also greatly restricts a blockchain’s performance characteristics (and blockchains are already inherently underperformant relative to their centralised counterparts, having to distribute state and all).

Ethereum has sought to reconcile this tension by pushing execution up one level of abstraction. With L2s, Ethereum can scale throughput and other performance characteristics all while retaining end-user verification of the base chain. While this is a clever hack, it comes at a cost of its own -- namely, fragmentation; of liquidity, state, and, to a lesser but nevertheless real enough extent, community. On the other hand, so-called ‘high-throughput’ chains, like the ones mentioned above, are unwilling to make this compromise, and have decided to optimise for performance and single-state instead. What this means in practice is that end users are dependent upon an honest majority assumption; that is, that the majority of block-producing nodes are reporting the correct state of the world. To be sure, this is an entirely legitimate tradeoff, and still a far better guarantee than the centralised world provides, but it nonetheless undermines this property that made crypto so democratic, and, ironically, subversive in the first place.

Fortunately, this historical tradeoff is not an inviolable law of nature. With technologies like data availability sampling and light clients, we already have the technology to thread the needle between performance and verifiability. With DAS and light clients, you can construct a system where the block producing / consensus nodes run arbitrarily powerful hardware, but still allow end-users to verify the state is as purported. That is to say, we can have our cake and eat it too.

Ultimately, verifiability is a concept that is easy to overlook amidst the far sexier notions in crypto. But it is nevertheless essential to a maximally just and democratic financial system; the noble north star towards which we’re all apparently building. Accordingly, we ought to assert this value wherever we can, so that it doesn’t go the way of so many good things before: gently into the good night.