I've been doing a bit of reading lately about the symbol grounding problem. Personally, I feel that this is possibly the greatest issue facing AI. Decades of research has not come close to solving it. I'm even starting to wonder if it could be a non-issue. After all, how do humans ground symbols? Neurons are simply on and off, like computers. Granted, there are neuron spikes; the timing can count. But how does that make it different from a computer at the lowest level?