“What a man believes upon grossly insufficient evidence is an index into his desires – desires of which he himself is often unconscious. If a man is offered a fact which goes against his instincts, he will scrutinise it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way.” - Bertrand Russell
Recent research provides more support for the view that much of our decision making is unconscious. In an experiment described in Unconscious buying at Neuromarketing blog, researchers showed fMRI brain activity relating to purchase decisions (which were predictable) even when volunteers were not paying attention to the relevant products. So whether or not they were consciously focusing on the products, brain activity could be used equally reliably to predict purchase decisions.
We are often (and perhaps almost always) unconscious of our decision making processes which our brain keeps hidden from conscious view for simplicity and efficiency. How reliable then are our conscious excuses for our unconscious decisions?