To many empiricist philosophers and scientists, AI seems to offer the best hope of defining, once and for all, a base for their way of thinking that can explain all of human thinking’s abstract processes and that is also materially observable. A program either runs or it doesn’t, and every line in it can be examined. If we could write a program that made a computer imitate human conversation so well that we couldn’t tell which was the computer responding and which was the human, we would have encoded what thinking is. At last, scientists had a beginning point beyond the challenges of the critics of empiricism and their endless counterexamples. (A layman’s view on how AI is faring can be found in Thomas Meltzer’s article in The Guardian, 17/4/2012.⁹)

Testability and replicability of the tests, I repeat, are the characteristics of modern empiricism and of all science. All else, to modern empiricists, has as much reality and as much reliability to it as creatures in a fantasy novel … amusing daydreams, nothing more.

                                                                    

                            

                                                   Kurt Gödel (credit: Wikimedia Commons) 

For years, the most optimistic of the empiricists were looking to AI for models of thinking that would work in the real world. Their position has been cut down in several ways since those early days. What exploded it for many was the proof found by Kurt Gödel, Einstein’s companion during his lunch hour walks at Princeton. Gödel showed that no rigorous system of symbols for expressing the most basic of human thinking routines can be a complete system. (In Gödel’s proof, the ideas he analyzed were basic axioms in arithmetic.) Gödel’s proof is difficult for laypersons to follow, but non-mathematicians don’t need to be able to do that formal logic in order to grasp what his proof implies about everyday thinking. (See Hofstadter for an accessible critique of Gödel.¹⁰)

                                                         

                      

                                                      Douglas Hofstadter (credit: Wikipedia) 

If we take what it says about arithmetic and extend that finding to all kinds of human thinking, Gödel’s proof says no symbol system exists for expressing our thoughts that will ever be good enough to allow us to express and discuss all the new ideas human minds can dream up. Furthermore, in principle, there can’t ever be any such system of expression.