Hoskinson Links Cardano’s eUTXO to Adam Back’s Advice

Charles Hoskinson wrote on October 9 that he followed Adam Back’s advice when developing Cardano’s extended UTXO model. Responding to Back’s recollection of a 2014 discussion with Ethereum’s early team, Hoskinson contrasted their subsequent paths: eUTXO for Cardano, and Simplicity and Liquid on Back’s side.

Hoskinson Responds to Back’s UTXO Recommendation

Back recalled recommending UTXO before the Ethereum team had written any code, rather than a balance-based model with active code and mutable state. He compared that advice with Buterin’s recent discussion of UTXO-based approaches, expressing frustration over the lack of acknowledgment for his earlier recommendation.

In a related post, Back described a warning he recalled giving the team. He argued that combining active virtual machine code with a balance-based actor and messaging model could produce race conditions, where interactions between operations and their ordering affect the outcome.

Back also stated that Hoskinson initiated the call, which included several other Ethereum technical founders.

Hoskinson responded:

“Well I did take your advice. We created EUTXO and you guys built simplicity and liquid.”

The exchange records their recollections of the discussion and Hoskinson’s explicit connection between the recommendation and his subsequent development direction.

Crypto Crow covered the posts in “Not So Fast… Watch This First,” interpreting them as recognition of Cardano’s architecture. Back’s statements focus on his recommendation and Ethereum’s early design; Hoskinson supplies the direct Cardano connection.

How Cardano’s eUTXO Supports Smart Contracts

UTXO stands for unspent transaction output. Funds are represented by outputs from earlier transactions, which new transactions consume and replace with new outputs. Each output can be spent only once.

A wallet displays a balance by adding together the outputs its user controls. When sending ADA, it selects suitable outputs and creates new ones for the recipient and any change returned to the sender.

Cardano’s eUTXO model extends this approach with data and smart contract rules. An output can carry data representing application state, while a validation script checks whether a transaction meets the conditions for spending locked funds.

Ethereum uses an account-based model, including contract accounts controlled by code. These accounts contain stored data that transaction execution can modify.

Developers therefore organize application state differently across the two networks.

Cardano transactions specify their actions, script arguments, and computational execution budgets in advance. Its documentation describes how developers can evaluate script behavior and calculate fees locally before submission.

That predictability does not remove competition for outputs. If another transaction spends a required input first, a prepared transaction can no longer consume it. Distributing application logic across multiple UTXOs is important for coordinating requests and enabling greater parallelism.

Buterin Outlines a Hybrid Ethereum Scaling Approach

In an August 16 post, Buterin described a proposed Ethereum scaling strategy combining the strongest features of UTXO-style state, dynamic state, and approaches between them.

He credited the Bitcoin community with pioneering several of these ideas, specifically mentioning Utreexo. His stated goal was to scale the great majority of Ethereum activity while preserving decentralization, ease of running a node, and censorship resistance.

The proposal concerns combining different ways of organizing state. Buterin’s post does not mention Cardano or its eUTXO model, and it describes a proposed direction rather than an adopted migration.

Cardano already uses eUTXO to represent contract state and validate transfers of ADA and other assets. Ethereum’s discussion concerns how UTXO-style techniques could fit alongside dynamic state in its future scaling architecture. Hoskinson’s response places Cardano’s existing model within that longer technical conversation, identifying Back’s recommendation as advice he chose to follow.