Michael says that everything should be code. If you accept the strong Church-Turing thesis and believe in the principles of digital physics, that the universe is indistinguishable from a computer simulation, then everything is already code.
But Michael means that representing everything as code should make collaboration easier. I argue that pseudocode is better. Do you really want to be reading and writing Java all day long? Because Java is the lingua franca. There is no question that you can express everything in Java, Java being Turing complete, but socially, pseudocode seems far more acceptable. For one thing, pseudocode is perennial.
David Brin also convinced me that natural languages have evolved the way they have, with their quirks and ambiguities, because this provides us with the necessary flexibility to be creative. Try being creative with Java. Bad idea.
Update: Peter Boothe points us to Marvin Minsky’s essay written in 1967, Why programming is a good medium for expressing poorly understood and sloppily formulated ideas.