Intent + skills = (almost) everything
Would we need encryption, contracts, etc of we could truly know a man's heart. If a promise given meant a deferred result guaranteed, then we could do away with much of the overhead of social and economic engagement.
But the heart of man remains a deeply guarded enigma. Many appear like the flower, but are the snake beneath.
There is still the random nature of existence that upsets the best-laid plans (hence the insurance industry), but societies could overcome much more with the ability to accurately assess intention and skill. 