John McCarthy's 1973 rebuttal to the Lighthill report dismissed control theory as having 'little relevance to AI'

Responding on his own Stanford venue to the Lighthill Report — which blamed AI's disappointments on the "combinatorial explosion" (claim-lighthill-1973-blamed-combinatorial-explosion) — John McCarthy, one of AI's founders and one of Lighthill's own named consultees, defended the field but conceded a specific boundary. In the same review he wrote that "many plausible mathematical theories with good theorems such as control theory or statistical decision theory have turned out to have little relevance to AI."

The same review shows McCarthy agreeing with the diagnosis itself: "the combinatorial explosion problem has been recognized in AI from the beginning, and the usual meaning of heuristic is a device for reducing this explosion" — confirming that both critic and defender framed intelligence as heuristic search fighting exponential blowup, the same search-vs-optimization framing at issue in claim-simon-satisficing-and-heuristic-search-same-move.

The dismissal of control theory is the load-bearing line: it is AI's own founder naming, by name, the discipline where the adjoint/gradient method — later rediscovered as backpropagation — was already mature and being taught to a generation of engineers (claim-bryson-ho-1969-curriculum-vector, claim-backprop-special-case-kelley-bryson-formula). McCarthy did not overlook optimal control; he considered it and ruled it irrelevant. That makes this a documented judgment rather than passive disciplinary blindness, of a piece with the disciplinary-contact gap the vault tracks elsewhere (claim-linnainmaa-field-numerical-analysis). See moc-backpropagation-origins.