What Is the Byzantine Generals' Problem? | Cryptocurrency Glossary

How Blockchain Overcomes the Byzantine Generals' Problem

The Byzantine Generals' Problem illustrates the difficulty of reaching consensus when nine military units of the Byzantine Empire are preparing to attack a certain country, and the generals leading the units must reach a decision by majority vote, which can lead to traitors emerging.

The nine armies encircle the target country but must decide whether to attack or retreat.
Each general sends messengers from their units to convey their decision. However, one general receives messages from four units indicating they intend to retreat, while four others indicate they intend to attack.

Believing that his decision would determine the majority vote, the general deliberately conveyed the intention to retreat to the units that had expressed a desire to retreat, and the intention to attack to the units that had expressed a desire to attack. This resulted in a disjointed response—four units retreating and four units attacking—leading to a situation where they were defeated by the nation they had attacked.

This serves as an example illustrating that the absence of a central authority and decision-making by majority vote carries risks. However, in Bitcoin, even without a central authority, the blockchain mechanism minimizes the scope for fraudsters to intervene. Since a blockchain continuously
records a chain of transactions, tampering with it requires significant effort. Consequently, it is more advantageous to process transactions correctly and earn rewards, leaving no room for fraud.