Apart from the question of whether a completely rational costs-and-benefits analysis of a decision is theoretically possible or not, our biological predisposition simply do not allow this. We feel, value and guess as we think. Although emotions cannot be prevented, they are, in fact, often quite helpful. They serve as automated mechanisms of decision, they signal and thus help us to anticipate, they reward and punish. In the end, emotions are, after all, much of what makes life worth living...
From the normative point of view, different amount of emotion-rationality ratio is desirable. An airline pilot landing in bad weather should not allow his gut feelings to perturb attention to the details on which decisions depend. In general, too much feeling at the smaller frames or too little at the larger frame can have disastrous consequences. But still, with the tremendous advance of science and technology, there is yet the possibility of pure rational thought in the concept of Artificial Intelligence. Nevertheless, also here, the human-like machines will need certain purpose of their existence; they will most probably be programmed in a way similar to how our mind works. Will ‘their’ emotions be recognized as ‘real Emotions’? Or, quite probably, will ‘our emotions’ still remain something unexplainable? These are questions that, like many others, need some time to be answered...