To simulate human brain on a computer most accurately, we would model each neuron and their connections. Then feed sensory data similar to what humans get from their eyes for instance. Looking at the activity of such a software brain we could monitor its synapses and see that they get activated in a similar manner as those in a real brain. Shouldn't we then assume it has "consciousness" as well? Would it "feel pain" for instance if we fed it appropriate sensory data?
No. Our software program simulating a brain is only a simulation of a real brain. What is simulation? It is a more or less accurate dynamic interactive description of something. But a simulation of a factory is not a factory. It is just a dynamic description of how a factory behaves, when we give it simulated inputs. The simulation is "isomorphic" (having structure similar) to a real factory, but it is not a factory.
Imagine taking a class in neurology. It is an e-learning course that gives you a fancy interactive web-page that shows how the brain reacts when you give it simulated stimulus. By using such an e-learning software you are able to understand how the brain functions. And in the coming years the fidelity and granularity of such dynamic brain-description software can be down to the level of individual neurons, including as many of them as in a real brain.
That e-learning application/simulation is still just a DESCRIPTION of the brain, not a real brain. It can behave just like a real brain would, just like a simulation of a factory could represent every action in a factory - yet not be a factory.
Think about software for weather forecasting. Meteorologists are ever improving their models of the weather to be as accurate as possible. They are simulating weather. But no-one would claim that a weather-forecasting application "is weather". It is just a dynamic, perhaps interactive description of it. It can't rain on you.
Conceptually a simulation does not differ much from an "interactive N-dimensional movie". We are familiar with 3D movies, but movies could also be N-dimensional. That would mean you can choose to view it from more than two viewpoints. Such a technologically advanced N-dimensional interactive movie would really be a "simulation".
Like movies, simulations can be replayed. They can be paused, and played backwards. If we say that software simulating the brain IS a brain, then we should similarly say that a (highly accurate interactive) movie of the brain is also a brain.
Such a movie could show us what happens in a human brain when we give it pain-inducing simulated inputs, That doesn't mean the movie is feeling pain.
In the end, does it really matter whether simulated pain is real, or not? It does from the viewpoint of ethics. It is unethical to cause unnecessary pain. But it is not unethical to DESCRIBE pain. Which is what simulation really is.
© 2013 Panu Viljamaa