Why is Geoffrey Hinton suspicious of backpropagation and wants AI to start over? - Quora

Backpropagation over deep neural networks has as much to do with the way the brain learns as modern jet airplanes have to do with the way birds fly. Both jets and birds fly, but they do so using entirely different principles. Jets do things birds cannot (fly at 500 miles per hour carrying many passengers), birds do things jets cannot (take off instantly). Each neuron is sending out "da dit da" messages like Morse code to neighboring neurons. The transfer functions are entirely different from RLUs or sigmoid.