Nobody and nothing, and this is generally impossible. Essentially what you do is just encode a trusted party (or multiple) and do what they say. This way you g

Nobody and nothing, and this is generally impossible. Essentially what you do is just encode a trusted party (or multiple) and do what they say. This way you get "trusted" data in the blockchain for scripts to use. For instance, who owns a house, or the closing price of a commodity, or who won the super bowl (or an election). As you can imagine this just makes them a target for corruption.