Your point about irrational thought brought to mind this Turing quote I really like: "If we want a machine to be intelligent, it can't also be infallible."

source: Lecture to the London Mathematical Society on 20 February 1947, pdf: http://www.vordenker.de/downloads/turing-vorlesung.pdf, also see this Quora answer for details: https://www.quora.com/What-did-Alan-Turing-mean-by-his-state...). Actually his exact phrasing is the reverse (on pg 13): "... if a machine is expected to be infallible, it cannot also be intelligent. "