German cognitive scientist, contemporary
Joscha Bach
The brain builds a model of the world, and inside that model, a model of a person. The person is a character in the brain's simulation, and only the character is conscious. Consciousness is real, but in the way a story or a piece of software is real: virtual, not physical.
The view
Bach is an AI researcher and cognitive scientist who has worked in Germany and the United States, including at MIT and Harvard. His book Principles of Synthetic Intelligence (2009) describes MicroPsi, a computational model of a mind built on the psychologist Dietrich Dörner's theory of motivation, emotion and cognition. Since then he has become widely known through lectures and long conversations in which he sets out a computational account of minds and consciousness.
His starting point is that a mind is software: a pattern of causal organisation, not a substance. The brain's main job is to build a model of the world good enough to steer a body. Because the organism's own body and states matter to that steering, the model includes a model of the organism itself. That self-model is the person you take yourself to be. Bach's slogan-sized version is that you are not the brain but the story the brain tells about a person living in its world.
The argument
Physical systems cannot be conscious; only simulations can. After Bach, in lectures and interviews
The claim sounds paradoxical, and it is meant to. Neurons do not feel anything; they only pass signals. But the model the neurons compute contains a world with colours, sounds and a self who sees and hears them. Within the model, it is perfectly true that someone experiences red. Outside it, at the level of physics, there is only activity. Asking where the experience is in the neurons is like asking where the dragon is in a computer's chips while it runs a game: the dragon is real at the level of the game, and nowhere at the level of the chips. Switch between the levels in the figure.
On this picture, consciousness has a job. Bach describes it as something like the conductor of the mind's orchestra, a process that keeps a coherent model going, notices what is new and binds the rest together. That makes it a target for engineering. If consciousness is a particular kind of self-organising model, then it could be built in a machine, and Bach thinks that understanding it is one of the most important problems in AI.
Where he meets Dennett
Very closely. Both are functionalists who think a mind is a pattern of organisation that could run on other hardware. Both think the self is a construction: Dennett's centre of narrative gravity and Bach's self-model in a simulation are versions of the same idea. Both treat our certainty that experience is irreducible as a product of how the model presents itself, and both are happy to say that, at the level of physics, there is no redness anywhere. Bach's view also sits close to Graziano's attention schema and Hofstadter's strange loop.
Where he parts
On words, and on emphasis. Dennett calls phenomenal consciousness an illusion. Bach prefers to say it is real but virtual: as real as anything in a simulation is, which, for the character living in it, is completely real. Dennett would say this is close to his own view in different dress, but the difference in tone matters. Bach's way of putting it invites us to take the simulated world seriously as the world we actually live in.
Bach is also more willing to speculate. He has suggested that consciousness may be a fairly simple and general learning principle, present early in development and perhaps widely in nature, and that machines with it could be built soon. Dennett was more cautious, and in his last years more worried about machines that only seem to be people than about machines that truly are.
| Bach | Dennett | |
|---|---|---|
| What is the mind? | Software: a model of the world, containing a model of a person. | What the brain does: a pattern of functions. |
| Is phenomenal consciousness real? | Real but virtual: it exists inside the simulation, not in the physics. | No, not as philosophers define it. It is an illusion produced by the brain. |
| Could a machine have a mind? | Yes, and conscious machines may not be far off. | Yes, in principle, if it does what we do. |
| Is there a hard problem? | No: it dissolves once levels of description are kept apart. | No. There is the Hard Question: and then what happens? |
Further reading
- Joscha Bach, Principles of Synthetic Intelligence: PSI, an Architecture of Motivated Cognition (Oxford, 2009).
- Joscha Bach's recorded lectures, including his talks at the Chaos Communication Congress, which set out the simulation view for general audiences.
- Thomas Metzinger, The Ego Tunnel (Basic Books, 2009): a related account of the self as a model the brain cannot recognise as a model.