Kantian ethics is explicitly governed by a spirit of universality. Universality is the one principle that drives everything else. Arguably, a concern for universality has been implicit in rational ethics since Plato and Aristotle, but Kant made it explicit and absolutely central; formulated it in a more rigorous way; and suggested several informal tests for it (the different formulations of the categorical imperative) that could be used in deliberation. Because it is possible to test maxims for compliance with the categorical imperative, Kant’s one principle can actually serve as a criterion, unlike Plato’s undefinable Good.
Universality implies no exceptions, so it can underwrite a kind of unconditional moral necessity that had no precedent in rational ethics before Kant. It seems that Kant wanted to contest Aristotle’s conclusion that ethics can never be an exact science. Kant borrowed talk about duty from what Brandom has called the traditional one-sided authority-obedience model of morality, but gave it new, rational, universal content. For Kant, every ethical decision should be approached as an instance and application of universal law. This means that in deliberation, we are not just deciding for ourselves what is right here and now, but what would be right for any rational being in similar circumstances. Kant wants us to act as universal legislators, and to respect the principle of humanity in every person.
There is something compelling about this, even for a convinced Aristotelian such as myself. Kant really did come up with something new. But also, Aristotelian sensitivity to particulars has been to an extent historically abused and hijacked by people with “particularist” agendas that Aristotle did not countenance, so a nudge in the direction of universality and respect for all humans is a welcome corrective.
This is not the end of the story. As I’ve noted numerous times, the absolute necessity of the categorical imperative applies only at an extremely abstract level, quite some distance from real-world application. I think this is at the core of Hegel’s impatience with Kantian “formalism”. Hegel is not quite fair to Kant, but Kant often seemed to want to claim he had reduced the whole of ethics to necessity, while directing our attention away from the parts he actually left open.
Next, I need to take a closer look at Kantian maxims, which are supposed to provide the bridge to real life. (See also Categorical Imperative; Kant’s Groundwork; Necessity in Normativity; Deontic; Binding.)