Comte argued against the Cartesian conception of the mind that the thinker cannot simultaneously think or perceive and observe itself so doing. Based on insights from cognitive neuroscience, Dehaene has recently given a contemporary answer to Comte’s challenge. He has extended some ideas of Helmholtz on unconscious inferences and argued that we can resolve Comte’s problem by reformulating it in terms of the brain. Since the brain consists of different parts having different functions, it is possible that some parts are (...) involved in observing (they unconsciously process information) while other parts integrate the received information resulting in conscious experiences to which we have access. Dehaene’s answer is criticized and the alternative neo-Aristotelian resolution of Comte’s challenge is discussed. Explanations of blindsight are used to illustrate the differences between the two responses to Comte’s challenge. (shrink)