Essays in games and decisions

In this dissertation, it is argued that the same mathematical object can be interpreted in different ways. For example, it can be a game, but it can also be a decision problem. Accordingly, the following question it raised: ‘Is it possible for a person to be perfectly rational in every situation?’ It is shown that a person can be simultaneously rational and irrational, which leads to a paradoxical situation. For example, while an individual can be perfectly rational with respect to financial decisions, the individual can make irrational decisions in his or her private life.