Final answer:
Kant posits that we must author our own moral laws because rationality distinguishes human agents, allowing us to derive universal moral duties. His categorical imperative rejects ethical relativism, offering a method to determine duties that apply to all rational beings. This upholds a universal basis for morality that is independent of cultural norms or divine command.
Step-by-step explanation:
According to Immanuel Kant, we must be the authors of our own moral laws because as rational agents, we have the unique capacity to exercise agency and will, making decisions based on reason rather than just following traditions or divine command. Kant's philosophy insists that ethical conduct must stem from a 'good will' and a duty carried out for its own sake, not merely for the benefits it might bring. Hence, instead of being guided by heterogeneous societal norms or a calculation of consequences, each individual should use their reason to determine universalizable principles of right action.
This need to author our own moral laws does not lead to ethical relativism. Rather, Kant proposed that through the use of our rationality, we can discover categorical imperatives, which are moral requirements that hold universally and necessarily. The categorical imperative demands that we act in a way that we would want our actions to become a universal law, applicable to all rational beings. This framework roots morality in universalizability and consistency, opposing the idea that morality is relative to cultural or individual difference.
Kant's ethical system is thus a robust third alternative to the poles of moral absolutism and normative ethical relativism, anchored in human rationality rather than divine command or subjective preference.