Human reasoning is often biased by intuitive heuristics. A key question is why some people are less susceptible to this bias than others. It is debated whether the bias results from a failure to monitor one’s intuitive conclusions for conflict with logical considerations or from a failure to inhibit the tempting intuitions. This results in different views on the role of individual differences in executive monitoring and inhibition capacity for sound reasoning. The present study presents a new approach to address this issue. After an initial reasoning screening a group of the most and least biased reasoners were invited for an EEG study in which neural markers of their executive monitoring (ERN amplitude) and inhibition (N2 amplitude) skills were recorded. Results indicated that biased reasoners were characterized by less developed inhibition but not monitoring capacity. Findings support the view that monitoring one’s intuition for conflict during thinking is a flawless and undemanding process suggesting that even the poorest reasoners at least detect that they are biased.