Warren McCulloch and Walter Pitts: A Logical Calculus of the Ideas Immanent in Nervous Activity

Abstract

The classical paper by McCulloch and Pitts on “a logical calculus of the ideas immanent in nervous activity” had an enormous impact on the development of brain theory in the broadest sense. It appeared in 1943 and was the starting point for many theoretical investigations up to the present day: its basic idea was that the activation of a neuron inside a brain stands for the actual truth of a proposition about the outside world. Elementary propositions about the outside world are verified through sensors. The neurons to which these sensors are connected may themselves represent more complicated combinations of these propositions. Since it is possible to implement the logical connections not, and, and or by means of neural connections and appropriate thresholds of the neurons, one can represent every conceivable finite logical combination of the elementary propositions in a neural network.