Why Perfect Fairness Cannot Hold in Asynchronous Networks and How Blockchains Relax It

Perfect fairness in asynchronous networks cannot be guaranteed, and blockchain systems address this limitation by adopting different, weaker forms of fairness. According to Cointelegraph, the core issue is that when a network does not provide reliable timing guarantees for message delivery, participants cannot ensure that transactions or messages are ordered and included in a way that is fully fair to all parties under all conditions.

The report explains that because asynchronous communication allows delays and uncertainty, any mechanism aiming for perfect fairness can be undermined by how information propagates and when different participants learn about competing actions. As a result, blockchain designs typically relax fairness rather than attempting to enforce an absolute standard that cannot consistently hold in such environments. Cointelegraph notes that different blockchains choose different trade-offs, implementing distinct fairness relaxations depending on their goals and assumptions about network behavior. These approaches vary by protocol, reflecting how each system balances ordering, inclusion, and resistance to advantages that may arise from timing and propagation differences across the network.