Section 1.2 Requirements
Consistency
Requirements 1.2
Parliament’s primary task was to determine the law of the land, which was defined by the sequence of decrees it passed ... each Paxon legislator maintained a ledger in which he recorded the numbered sequence of decrees that were passed. ... Ledgers were written with indelible ink, and their entries could not be changed.LAMPORT, P. 3 — §1.2
Stripped of allegory this lays out the idea of node/legislator and their ledger. Ledgers are a ordered list of decrees/values that once entered cannot be changed.
Requirements 1.2
The first requirement of the parliamentary protocol was the consistency of ledgers, meaning that no two ledgers could contain contradictory information. Then no other legislator’s ledger could have a different entry for decree ... However, another legislator might have no entry in his ledger for decree 132 if he hadn’t yet learned that the decree had been passed.LAMPORT, P. 3 — §1.2
Liveliness
Requirements 1.2
If a majority of the legislators were in the Chamber and no one entered or left the Chamber for a sufficiently long period of time then any decree proposed by a legislator in the Chamber would be passed, and every decree that had been passed would appear in the ledger of every legislator in the Chamber.LAMPORT, P. 3 — §1.2
Given enough time if a value for a decree has been proposed some value for the decree will be learned by the node
Validity
Finally, a third requirement that isn't directly defined is that any value learned must be proposed. IE the nodes must use the algorithm and not ignore the directives and do their own thing.