Reasoning and decision making
Reasoning is often seen as a panacea in decision making. By following rules, lengthily comparing the pros and cons, we are supposed to reach the best solutions. While these techniques can certainly be efficient, a flurry of recent work shows that they sometimes drive us towards bad outcomes. However, bad as they may be, these outcomes seem to share a characteristic: we can justify them. This is a telltale sign that reasoning, under the guise of an argumentative device, has done its job: not make better decisions overall, but decisions that we can defend.
Some of the evidence supporting this idea can be found here. I am also working on a paper that will offer a much more detailed view of the role reasoning plays in decision making.