Final answer:
Sebastian is in the preconventional stage of moral development, specifically experiencing heteronomous morality, as his decision is based on avoiding punishment rather than on societal norms or ethical principles.
Step-by-step explanation:
In the scenario provided, Sebastian demonstrates a level of moral reasoning known as heteronomous morality, which is part of Kohlberg's preconventional stage of moral development. This stage is typical for children before the age of 9, as they base their moral decisions on the consequences of their actions, such as receiving punishment or rewards, rather than on societal norms or higher ethical principles.
Therefore, Sebastian's decision to take only two cookies, influenced by his desire to avoid a negative consequence (time out) rather than an understanding of fairness or societal rules, supports the conclusion that he is operating within the preconventional stage of moral development, specifically heteronomous morality.