“Act in such a way that you treat humanity, whether in your own person or in the person of any other, never merely as a means to an end, but always at the same time as an end.”
In this quote, Kant formulates his categorical imperative, which he insists is the only correct basis for properly moral action. By formulating an action as the basis for a universal moral law, we can strip it of the incentives and the calculations that make it purely situational.
A good will is good not because of what it effects, or accomplishes, not because of its fitness to attain some intended end, but good just by its willing, i.e. in itself; and, considered by itself, it is to be esteemed beyond compare much higher than anything that could ever be brought about by it in favor of some inclinations, and indeed, if you will, the sum of all inclinations. Even if by some particular disfavor of fate, or by the scanty endowment of a stepmotherly nature, this will should entirely lack the capacity to carry through its purpose; if despite its greatest striving it should still accomplish nothing, and only the good will were to remain (not of course, as a mere wish, but as the summoning of all means that are within our control); then, like a jewel, it would still shine by itself, as something that has full worth in itself.
Here Kant immediately positions his moral theory against the theory of moral sentiments worked out by David Hume and Adam Smith, as well as against the popular belief, later worked out by the utilitarian philosophers of the nineteenth century, that whatever makes people happy must be moral. Kant argues that moral actions have to be good in and of themselves, and the only way for that to be the case would be if we were able to determine that in their very logical form, that is, independently of their motivations and results, they were moral.
"If adversity and hopeless grief have quite taken away the taste for life; if an unfortunate man, strong of soul and more indignant about his fate than despondent or dejected, wishes for death and yet preserves his life without loving it, not from inclination or fear but from duty, then his maxim has moral content.”
In this quote Kant intends to show that inclination cannot be the basis for moral action because often only those judgments have moral worth that run against inclination. In this example, he imagines a person who finds no joy in life who nonetheless continues living because they accept that they have a duty to do so. Kant suggests that this decision would have a moral value. Conversely, if the man had decided to live but only because he enjoyed life, that decision would not have a moral value. This aspect of Kant's moral philosophy has found many detractors, including the poet Friedrich Schiller, who observed that Kant seemed to believe that human beings had to constantly watch themselves to make sure they didn't enjoy doing the right thing. The Christian flavor of Kant's argument--finding an analog in, say the idea that the return of the prodigal son brings more joy to the father than the continued goodness of the son who stays home—is particularly present here.
Innocence is a splendid thing, only it has the misfortune not to keep very well and to be easily misled.
Here Kant considers the possible popular application of his argument. He believes that because of its relative simplicity, and because it is grounded in reason, which every person possesses, each person already possesses the capability for moral action. Philosophy does not need to teach people to be moral. Rather, philosophy acts as more of a corrective, so that people can consult it to make certain that they aren't misleading themselves, and confusing their inclinations for objective moral judgments.
The will is conceived as a faculty of determining oneself to action in accordance with the conception of certain laws. And such a faculty can be found only in rational beings.
Here Kant offers his definition of the will, which, we might note, is rather different from how usually think of the will. Typically, we understand the will to be that part of our mind that initiates action, the part of us that decides to do something and then makes sure we do it. Kant believes that this part of our mind is active and conscious, unlike our instincts, which are passive, and unconscious. For it to be active, that means it has to be rational, and for it to be rational, that means that it has to act according to laws and principles, instead of just inclinations.
Act in such a way that you treat humanity, whether in your own person or in the person of another, always at the same time as an end and never simply as a means.
Here Kant expresses his view that the only basis for legitimate moral action is to treat other human beings as though they are ends in themselves. Because the will, which is the basis for moral action, is really a way of matching means and ends according to laws, the only means and the only ends that are universally, rationally grounded, and therefore in accordance with the law, is the dignity and worthiness of man. In this quote we can clearly see the humanist side of Kant; since Kant's time, "human dignity" has become an important legal concept in national constitutions as well as in medical ethics, where it crops up in debates on subjects like assisted suicide.
[A man] finds himself forced by necessity to borrow money. He knows that he will not be able to repay it, but sees also that nothing will be lent to him unless he promises stoutly to repay it in definite time. He desires to make this promise, but he has still so much conscience as to ask himself: Is it not unlawful and inconsistent with duty to get out of a difficulty in this way? Suppose, however, that he resolves to do so, then the maxim of his action would be expressed thus: When I think myself in want of money, I will borrow money and promise to repay it, although I know that I never can do so. Now this principle of self-love or of one's own advantage may perhaps be consistent with my whole future welfare; but the question now is, Is it right? I change then the suggestion of self-love into a universal law, and state the question thus: How would it be if my maxim were a universal law? Then I see at once that it could never hold as a universal law of nature, but would necessarily contradict itself. For supposing it to be a universal law that everyone when he thinks himself in a difficulty should be able to promise whatever he pleases, with the purpose of not keeping his promise, the promise itself would become impossible, as well as the end that one might have in view in it, since no one would consider that anything was promised to him, but would ridicule all such statements as vain pretenses.
In this quote, Kant walks us through an example of the categorical imperative in action. The person who wants to borrow money without repaying cannot legitimately use the categorical imperative to ground his action, because, if that were the case, then no one would ever lend anyone money. He will have created a hypothetical world in which everyone swindles everyone else as a matter of course. Philosophers have debated whether the situation here does indeed contain a contradiction, as Kant says it does; if, for example, the person from whom he was borrowing money would not miss it if it were lost, the maxim could be formulated as, "Never act in such a way that harms others." Kant's conclusion makes more sense from the perspective of the maxim never to use others as means, but only as ends in themselves. By borrowing money we never intend to repay, we treat our lender as a means, diminishing his dignity.
The sight of a being who is not graced by any touch of a pure and good will but who yet enjoys an uninterrupted prosperity can never delight a rational and impartial spectator. Thus a good will seems to constitute the indispensable condition of being even worthy of happiness.”
Hannah Arendt has observed that the notion of being "worthy" of happiness repeats again and again in Kant's writing, and is generally a concern that he applies to himself. Arendt argues that Kant conceives of ethics and of morality as a kind of inner harmony, a way of bringing together one's reason and one's inclination. The universal aspect of Kant's thought is a way of imagining this possible harmony, which would also harmonize the rational and the sensory aspects of our existence, the part that judges what is worthy of happiness and the part that feels pleasure. We can also detect traces of the classical philosophical notion that pleasure and true happiness are in fact distinct, and that they often run counter to one another.
Moral instruction, although containing much that is convincing for the reason, ...accomplishes... little... [because] the teachers themselves have not got their own notions clear, and when they endeavor to make up for this by raking up motives of moral goodness from every quarter, trying to make their physic right strong, they spoil it.
Here Kant stresses the need for his Metaphysics, and explains what it has to contribute to our daily understanding of morality. Kant believes that his philosophy will help us to use our reason to determine moral laws for ourselves. No one else can do this for us, we have to take responsibility for our own moral improvement, and we have to use our reason to make absolutely certain that the concepts we are using are truly sound.
Nature generally in the distribution of her capacities has adapted the means to the end... [so nature's] true destination must be to produce a will, not merely good as a means to something else, but good in itself, for which reason was... imparted to us as a practical... absolutely necessary... faculty.
This quote brings the Groundwork for the Metaphysics of Morals in line with Kant's anthropology, something that he would explore in the last years of his life. Kant believed that nature was a progressive process that gradually steered man towards perfection, though no one individual would ever live to see the process completed. What we think of as "culture," i.e., our reason, including our capacity for philosophy, are in fact tools that nature has given us to ensure that we can participate in this process of perfection.