Many ideas in ethics are getting synthesized in contemporary views, and I would like to share some thoughts on that, concerning Kant’s deontological ethics, and how they might possibly tie into systems like Hume’s, as well as consequential theories, through biological determinism.

I recently read Raw Langton’s, Maria von Herbert’s Challenge to Kant (http://homepages.ed.ac.uk/rhl/maria.html). I was thoroughly impressed. I have heard plenty of criticisms of Kant's ethics having the tendency to reduce people to something like cold, desensitized robots, but never have I seen such a vivid and moving example of that. It was kind of inspiring, in a way.

I think the popular consensus is that Kant's rejection of emotion's role in ethics was unwise, but I haven't really been able to see or say exactly why and how, until now. Of course, popular consensus and emotional response does not establish truth, so this isn’t a criticism in itself—this problem is probably actually the motivation for Kant’s discussion of ethics, or any attempt to establish a solid system determining moral truths for that matter.

I do think there are some inclinations that we'd do better without, but, that’s only because I am looking at inclinations with the end of efficiency and harmony in mind. There are some strong parallels to this in the idea of being moral to join with God, or being moral to transcend nature or worldliness, which is said to be the source of suffering or wickedness. But, I don’t view nature as evil. I rather recognize that the goal of humans to be liberated from suffering is incompatible with nature, including human nature. But, I don’t think that it’s wholly impossible, irrational, or futile. Technology and knowledge, with proper application, has done much to relieve the terrible suffering that other animals endure in nature. I see no reason that if this progress were to extend into the far future that suffering could be greatly diminished, perhaps even virtually eliminated. And, this would require some control and perhaps elimination of our natural drives or inclinations; but, not all of them. The ones that agree with and support efficiency, cooperation, and harmony between people are beneficial to the process. Once again, this is a teleological process—ultimately a utilitarian one. Otherwise, it would serve no purpose, other than self-perpetuation.
Maybe that’s what Kant intended for the Kingdom of Ends, self perpetuation, but—like Langton criticizes—we have to get there first! And, goal accomplishment is conditional; it requires a consequential approach.
I agree with Langton (and others) that nature is indifferent to our individual happiness, suffering, or attempts to reconcile our ideas of ‘good’ as being inherent in nature. 'Indifferent' is probably too anthropomorphic a term to accurately describe it even. Nature encompasses humanity, and giving rise to our reason and our ethics, it engulfs our attempts to separate ethics from it and base it some alternative source or set it up as a standalone system.

The foundation of human ethics itself may very well be an emergent psychological phenomenon in nature that serves a function which is not unique to humans, but just more elegant. But, inclinations and reason both emerge in nature, and serve a function for the organisms in which they emerge.

Kant’s complete rejection of emotion and inclination make his ethics cold and logical. A robot could follow Kant’s ethics; he is like an 18th century Spock. I am sure that’s not a new connection. Maybe Kant even provided some inspiration for the character. I appreciate his ‘good intentions’, but I don’t agree with his complete rejection of inclinations. I think the Kant’s work on establishing a logical basis for ethics (or for anyone to try to establish a logical basis for understanding anything, for that matter), is necessarily based on an inclination to do so, and if this is so, then to reject inclination would be self-defeating. This is, I think, subtly suggested in Nietzsche’s short criticism of Kant in Beyond Good and Evil.
Hume’s ethics are commonly cited as opposed to Kant’s in that they rest on inclinations. He separates matters of fact—propositions describing the natural world and “relations of ideas”, or ‘what is the case’—from matters of emotion or “passions”. I don’t see that Kant really answered or directly criticized Hume’s ideas. Instead he formed a distinct, contrary presentation of morality. But, Hume’s conclusion that moral judgments are not conclusions of reason, and is rather in agreement with the popular view that morality and emotions are deeply intertwined, is from just as cogent an argument as Kant’s, if we overlook the criticism that Kant’s was inclined by his passion to found ethics on reason. But, if Kant’s ethics are fundamentally founded on a passion—as Nietzsche says, “[Kant] want[s] us to understand with [his] morality: ‘What is respectable about me is that I can obey—and things should be no different for you than they are for me.’”—then Kant’s and Hume’s ethics are not wholly incompatible.
Kant’s ethics are counter-intuitive, but I see it as an honest attempts to solve Hume’s ‘is/ought problem’. Hume resolved it by just admitting that moral truths are not really based on absolute truths, and are somewhat subjective. I’ve read criticisms of Hume suggesting he advocated relativism, or some kind of proto-relativism, but I don’t agree with this. Hume definitely says that some “passions” and “principles of taste” are universal. That suggests that there is some kind of universal human moral values on which a system of ethics could rest. If we can determine what these are, and establish them as axioms, it would be a real possibility to develop a system of morality as logical as mathematics, but in also in strict agreement with the common human moral sentiments. And, I think these moral inclinations or “passions” that we share are so intricate and impressionable that they can be affected by reason and beliefs, but so universal that—as Sterba suggests in his introduction to Ethics: Classical Western Texts in Feminist and Multicultural Perspectives—if we shared the same background beliefs, we’d most probably always share the same moral judgments.

Suppose this elusive universality really does exist; it would make sense to hypothesize that it arises from, and fundamentally depends on our biological makeup. And, this is something that can be empirically tested, and may eventually be established (or falsified). If this were true, we could definitely synthesize Kant and Hume’s ideas on ethics, and establish Langton’s aphorism, “Inclinations without reasons are blind…, reasons without inclinations are empty.”