The formal study of valid inference; Boolean algebra applies algebra to logic and provides the language for describing automata and neural nets.
Young is sceptical of pure logical theory but credits McCulloch and Pitts' use of Boolean logic to describe neural networks, opening the nervous system to computer-engineering methods.
George develops formal logic from relational statements and the syllogism, making symbolic logic a cornerstone of cybernetics — the bridge from theory to buildable construction.