Full Idea
The most important thing that has happened in cognitive science was Turing's invention of the notion of mechanical rationality (because some inferences are rational in virtue of the syntax of their sentences).
Gist of Idea
Turing invented the idea of mechanical rationality (just based on syntax)
Source
Jerry A. Fodor (In a Critical Condition [2000], Ch.17)
Book Reference
Fodor,Jerry A.: 'In Critical Condition' [MIT 2000], p.204