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Weak Subjectivity


‘Weak subjectivity’ refers to the requirement for specific nodes to rely on other nodes when determining the current state of a proof-of-stake (POS) blockchain. The concept was created by Vitalik Buterin.

Understanding the Term

‘Weak subjectivity’ is used to figure out which chain is active. Essentially, it’s regarded to be weak since it occurs exclusively in two situations:

?   When a new node joins the network

?   When a node has been offline for a significant period of time

Therefore, when a node is online all the time, there will be no issues with subjectivity. Merely because it will be able to immediately identify whether the PoS blockchain is legitimate.

However, if a node went offline for an extended period of time or just joined the network, it will have to rely on other nodes. This is exactly when subjectivity comes into play.


Weak subjectivity is, thus, related to the idea that new and recently inactive nodes remain secure by their need to receive information from other nodes when trying to determine the validity of the blockchain.

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