I've constructed a simple thought experiment: someone walks into a convenience store, with lots of money spilling out of the cash register, poor convenience store worker dead from a heart attack, and different 'people,' motivated by pure philosophic principles, enter the convenience store. What do they do?
There's two Hobbes: simple and slightly more complex. The simple Hobbes is found in Chpater VI of Leviathan
But whatsoever is the object of any man's appetite or desire, that is it which he for his part calleth good: and the object of his hate and aversion, evil; and of his contempt, vile and inconsiderable. For these words of good, evil, and contemptible, are ever used with relation to the person that useth them: there being nothing simply and absolutely so; nor any common rule of good and evil, to be taken from the nature of the objects themselves; but from the person of the man (where there is no commonwealth;) or, (in a commonwealth,) from the person that representeth it; or from an arbitrator or judge, whom men disagreeing shall by consent set up, and make his sentence the rule thereof.
We're driven by appetites and aversions, but we're immediately quite different from animals. Animals are driven by appetite and aversion, and that's it. But humans immediately put a moral connotation on what they like and dislike, calling them 'good' and 'evil.' And so a Hobbesian walks into our fictional convenience store. He certainly takes the money (all surveillance cameras are dead; think of New Orleans), but he also finds some way to justify and rationalize what he's done. "Well, this money ain't no good to the dead convenience store worker," or "Insurance company will just reimburse the corporation behind the convenience store anyway; no harm no foul."
In a New Orleans-type situation, the basis of political obligation has been ripped apart:
To this warre of every man against every man, this also is consequent; that nothing can be Unjust. The notions of Right and Wrong, Justice and Injustice have there no place. Where there is no common Power, there is no Law: where no Law, no Injustice....It is consequent also to the same condition, that there be no Propriety, no Dominion, no Mine and Thine distinct; but onely that to be every mans that he can get; and for so long, as he can keep it. Lev. Ch. 13
In New Orleans there was no 'common power,' or at least it was awfully weak. All bets are off: I take what I can get.
That's the simple Hobbes. And perhaps even this simple Hobbes is too simple.
But I'm ready to grant that there is a more complex one. It depends on how much weight you want to put on Hobbes' treatment of language. As we've seen, Hobbes makes clear the tight link, the one-right-after-the-other, nearly simultaneous relation between appetite-aversion and values-language.
Sixthly, it is annexed to the sovereignty, to be judge of what opinions and doctrines are averse, and what conducing to peace; and consequently, on what occasions, how far, and what, men are to be trusted withal, in speaking to multitudes of people; and who shall examine the doctrines of all books before they be published. For the actions of men proceed from their opinions; and in the well-governing of opinions, consisteth the well-governing of men's actions, in order to their peace, and concord. Lev Part 2, Ch. 18
Depending on how well a sovereign can manage the "opinions and doctrines" of the people, their very aversions and desires might be controlled. Our appetites toward and from objects produce 'opinions' of what is harmful and beneficial, which quickly turn into valuations about what is 'good' and 'evil.' The Sovereign can try to work backwards: controlling opinions of right and wrong, helpful and harmful, so as to control the anarchic tendencies of the appetite-driven human subject.
If a competent Sovereign were able to pull this off, then a Hobbesian agent might have socialized notions of good and evil successfully implanted, thus keeping the agent from taking advantage of the situation found in the convenience store.
Okay, what about a Kantian? Here we have the Enlightenment in full bloom. It might seem that someone like Hobbes is the most 'rationalist' of the philosophers from this tradition, with his idea that humans pursue this or that desire, using reason to calculate costs, benefits, and means. Our use of reason is meant to be more elevated than that.
On what ground 'meant' to be more elevated? Kant uses a teleological argument to convince us that employing reason as a mere 'slave of the passions,' as Hume put it, is not really to use reason at all.
Everything in nature works according to laws. Rational beings alone have the faculty of acting according to the conception of laws, that is according to principles, i.e., have a will. (Kant, Groundwork, Second Section)
I think his argument is that because, unlike everything else in nature, we are able to give ourselves laws, that then is the highest activity we are capable of. The fullest activity. In this way, Kant can be seen to have a kind of "expressive" view of human nature, just like Aristotle, or Charles Taylor. When we merely calculate means, ends, etc., we are not fulfilling reason's potential. To do so, we have to do what nothing else in the universe can do: give ourselves laws.
Of course we can talk about Kant forever but maybe I've said enough to clarify what the Kantian agent would do in the convenience store. She would recall the law she has made for herself; one that has not been imposed, either 'consciously' by a supreme being or 'socially' by a competent, Hobbesian sovereign. It is "do not steal from other human beings." She walks away with nothing. What has motivated her? Not pity or concern for others. Her focus, rather, is to act in a way that maintains the commitment to a value that transcends in importance the fleeting benefits gotten from pocketing a few thousand extra dollars without the risk of getting caught. It's like she's a kind of human god who fears acting in a way that will betray and undermine her godhood. Her godly power is: making her own laws; in a word, autonomy. If she breaks her own law, she loses her humanity. And who would want to trade one's humanity (or godliness, if we prefer) for a lousy few thousand bucks?