The main goal of this study is to examine whether instrumental rationality can explain successfully human behavior in all walks of life. The rational choice theory and the public choice theory are chosen as the focus of the investigation, since they are considered as the best models of instrumental rationality. To see their merits and to determine their limits, the theories have been applied to the problems of culture and identity. Even though the choice theories have relative success in explaining the complexity and subtlety of cultural behaviors, instrumental rationality still retains its philosophical value in investigating and predicting human decisions and acts.