Abstract
Current research on morality is divided into rationalist and intuitionist theories. This study shows that when individuals make rational choices, they are inevitably guided by the moral foundation of intuitionism. Especially to pursue self-interest, individuals must agree with others in society. They must keep their opinions constant to agree with others. To maintain a constant opinion, the individual assigns an opinion that can improve the utility of the other person and place both of them in the same situation. The actions taken by an individual must be altruistic to enhance the utility of the other person . The individual’s opinion is subsequently guided by the golden rule of morality, “Treat others as you would like to be treated,” which facilitates moral foundations.