Final answer:
The statement is true; Kant's duty-based ethical theory does emphasize a single principle of duty through the concept of categorical imperatives. Critics like William David Ross argue that this approach over-simplifies moral life by not taking into account the complexity of conflicting obligations.
Step-by-step explanation:
The statement about Kant's duty-based theory of ethics emphasizing a single principle of duty is true. Immanuel Kant advanced a deontological ethical theory which is based on the notion that actions are intrinsically right or wrong, and moral rules are absolute. His approach is centralized around the concept of categorical imperatives, which are universal moral laws that any rational being would accept. However, Kant's theory has been critiqued by philosophers such as Sir William David Ross for over-simplifying moral life and inadequately accounting for the common human experience of morality. Ross introduced the idea of pluralistic deontology, suggesting that our duties are not absolute but rather prima facie, meaning they are binding unless overridden by a more pressing duty in a particular situation.
When evaluating moral dilemmas, Ross's theory considers the competing obligations and reinforces the understanding that our actual duty is the one most pressing and immediate. This adds a layer of complexity to ethical decision-making, contrasting with Kant's idea of perfect duties which we are obliged to follow at all times. Kant's focus on the intention behind actions and the role of a good will remains pivotal in discussions of ethical progress and the development of a just society.