title: Do we really need a notary that validates?
body: <p>At the risk of sounding naive, I ask myself "Is a validating notary necessary?", given all the issues with it - transaction and dependencies leak, exposure of state model, to name a few.
  The answer I hear has something to do with the potential attack where a dishonest node tries to steal someone else's asset. For example, in a legitimate transaction, partyA sold partyB some asset S subject to a Move contract. Immediately afterwards, partyA creates a self-signed transaction that transfers S back to himself subject to a dummy contract in a bogus flow that does not even run the ledger transaction verify(). But when he calls FinaltyFlow to satisfy the simple notary to commit the transaction on the ledger, it will fail the verifyContracts() because S appoints to the Move contract which should say owner partyB must sign the bogus transaction. 
  So that does not convince me of the need for a validating notary.
  Apparently, I must have missed something. Can someone enlighten me?</p>
  
  <p>Thanks.</p>
  
  <p>\Sean</p>