4 NEURAL NETWORKS AND DEEP LEARNING

Our brains make us intelligent; we see or hear, learn and remember, plan and act thanks to our brains. In trying to build machines to have such abilities then, our immediate source of inspiration is the human brain, just as birds were the source of inspiration in our early attempts to fly. What we would like to do is to look at how the brain works and try to come up with an understanding of how it does what it does. But we want to have an explanation that is independent of the particular implementation details—this is what we called the computational theory when we discussed levels of analysis in chapter 1. If we can extract such an abstract, mathematical description, we can later implement it with what we have at our disposal as engineers— for example, in silicon and running on electricity.