When we have to make a decision, we consider all the pros and cons, try to gather a lot of information and estimate what consequences this decision might have. And then we make an (at least somewhat) rational decision. Or do we?
Petter Johansson, a cognitive scientist at Lund University, presents results from experiments he conducted and suggests: More often than not, it is only after we have made our choices, that we come up with reasons for it.
Very relevant evidence for the absence of rationality in decision making.