My take is that ‘truth’ exists outside of the systems we are building.
What we are engineering are systems that have global consistency - nothing to do with ‘global truth’. For example, in #nostr there is no such thing as conflicting events - each has their own identity (hashed ids) signed by a cryptographic identity (npub) whose private key is also ‘outside of the system’
So, there is no ‘global source of truth’, or complete picture, but the parts we each have (signed events) can form a part of a larger and consistent picture.