If you enter a taxi and tell the driver where you want to go, you can just lean back and relax. The driver will do the rest. He will decide a route to go and drive along that route. He will take care of avoiding collisions with other cars, with bikes or pedestrians. He will turn the steering wheel and press the pedals etc. The only additional thing you have to do is to pay and get off.
So the passenger, while in the cab, resides in a world that contains his place of departure and his destination, and to get to that destination, he gives a simple command, later the driver tells him they have arrived and how much he has to pay. His world is simple.
The world of the driver, on the other hand, contains the gas pedal, the steering wheel, the other cars outside, the streets, crossings and roundabouts, red lights, traffic signs and traffic rules and many other items. It is a lot more complex than the world of the passenger.
The driver, in turn, operates the car through a relatively simple interface, consisting or steering wheel, gear lever, some pedals and some switches. This user interface connects him to a system consisting of mechanical, electric and (in more modern cars) electronic and software components. The passengers request, let’s say “Regent’s Park, please”, is translated by the driver into movements of the different controls. These translate it again into electronic signals, electrical currents, chemical processes of combustion and mechanical movements. If we take a closer look at the microprocessors and the software running on them, we would find a hierarchy of programs running each on top of the services of the ones below, with a level of programs operating the hardware that are called “drivers”, a term probably coined with a car driver in mind.
On the interfaces from passenger to driver and from driver to car, from high level software to low level software and to hardware, the components or concepts in terms of which the whole process can be described are changing. The language of description is changing. Moreover, processes and objects on one level may be hidden to an observer or user on another level, thus presenting a simplified view of the system. The underlying system emulates a simpler system and presents a “world” consisting of simpler objects with simpler properties and “controls” of interaction.
I am calling the transition from one conceptual world to another an “ontological transit”. Some system (a “driver”, and here I mean the term not in the narrow technical sense of computer technology or cab driving) creates a simplified view of the system enabling it to be observed or operated in terms of a different language. On the “passenger’s” level, objects exist that might not exist or have a different structure and meaning on the level below the “driver”. One may think of the driver as creating an as-if-construction, constructing a new world of objects from different “underlying” ones, a relationship that could also be called “emulation”. When the passenger looks out of the cab and sees a bus, there is something in his brain translating red dots into the image of a bus and maybe a thought like “there is a bus”. We can think of each concept shaping his or her perception this way as a “driver”, something like a piece of software translating a world of pixels into a world of objects.
If we take a closer look at the cab driver, we might notice that some of the things that seemed to constitute his world are actually out of his consciousness most of the time. He will operate most of the car’s controls automatically. So there is something like a passenger-driver-interface inside his brain as well. He does not have to think about pressing the gas pedal or switching the gear. He will do it automatically. In a way, he might even experience the car as an extension of his body. And he does not have to think about moving his arm or hand or finger. He will not be aware of the single muscles involved in those movements and of the nerves that send the signals to them from the brain. He will not be aware of the processing of the primary signals from his eyes and ears into a three dimensional experience containing cars, pedestrians and traffic signs, something that might appear as raw sense data to him but actually is already the result of complex computations.
And he will not be aware of the chemical processes inside his nerves and muscle cells, of all the organelles and enzymes, the reactions of molecules, of the citric acid cycle and the RNA transcription at his ribosomes and all the other processes of his metabolism, nor of the exchanges of electrons and protons involved and the processes underlying these on the atomic and sub-atomic level. This may be described as a number of layers of description each constituting a different “world” of objects, properties and processes.
The taxi arrives. “Regent’s Park, sir, 5 pounds 20”.
(The picture is from http://commons.wikimedia.org/wiki/File:London_taxi_(2847060661).jpg?uselang=de)